Desperate defending from Portugal as Matt Doherty's effort is charged down by Joao Moutinho.
Can the Republic get a winner?
Post update
Republic of Ireland 0-0 Portugal
Rafael Leao only came on in the 56th minute, but he's replaced in the 83rd minute as Portugal looks to solidify their defence after that Pepe red card.
Ex-Southampton man Jose Fonte, now at French side Lille, is the man on, with Leao replaced.
RED CARD - Pepe (Portugal)
Republic of Ireland 0-0 Portugal
He got booked for dissent 10 minutes earlier, and now Pepe has seen red. He catches Callum Robinson in the face with a stray elbow, and that's a second yellow and Portugal are down to 10.
A real chance for the Republic now to win this.
Post update
Republic of Ireland 0-0 Portugal
That Enda Stevens miss is his last action as he and Jeff Hendrick go off, with James McClean and Conor Hourihane coming on.
Ronaldo, to the home fans' concern, is seeing more of the ball now and has just curled one wide. Just over 10 minutes plus injury time to go.
Seven for Croatia
Anything you can do....
Russia thrashed Cyprus 6-0 earlier, so Group H rivals Croatia have responded by hitting seven against Malta. It's 7-1 now.
Sunday's showdown for top spot between Russia and Croatia is going to be a cracker.
Getty ImagesCopyright: Getty Images
Post update
Republic of Ireland 0-0 Portugal
Some more changes for Portugal. The extremely quiet Bruno Fernandes is off, as is Andre Silva, with Joao Felix and Renato Sanches on.
Moments later the hosts have a chance but Enda Stevens is not the man you want in the situation and he balloons it over the bar after being played in by Chiedozie Ogbene.
Post update
Republic of Ireland 0-0 Portugal
Pepe is shown a yellow for dissent after a clear handball, but the Republic waste the free-kick.
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Republic of Ireland 0-0 Portugal
A booking for Danilo, who is completely done for pace by a sprinting Chiedozie Ogbene down the right flank.
Cynical from Danilo and a deserved yellow.
Post update
Republic of Ireland 0-0 Portugal
Nearly, so nearly for Ronaldo. A cross comes in from the left and he gets above Jeff Hendrick with a glancing header.
Goalkeeper Gavin Bazunu is panicking and at full stretch, but luckily for him, Ronaldo's header is just wide.
Moments afterwards, someone runs on to the pitch aiming for Ronaldo, but the intruder is quickly grabbed by security before getting anywhere near the Manchester United man.
Post update
Republic of Ireland 0-0 Portugal
It's been an excellent defensive performance so far from the Republic. Shane Duffy, in his 50th appearance, shows his strength to shield the ball behind under pressure from substitute Rafael Leao.
Cristiano Ronaldo and Bruno Fernandes have been very, very quiet so far. But we all saw what happened in the first match between these two late on.
Goals galore
Andrek Kramaric now has Croatia 6-1 ahead in Malta, while Leroy Sane puts Germany 5-0 ahead against 10-man Liechtenstein.
SUBSTITUTION
Republic of Ireland 0-0 Portugal (19:45 GMT)
A change for the Republic with Norwich striker Adam Idah on for Jamie McGrath.
Post update
Republic of Ireland 0-0 Portugal
Matt Doherty, close to the dead ball line, manages to squeeze out a cross but Rui Patricio is off his line to dominate the area and end the attack.
SUBSTITUTIONS
Republic of Ireland 0-0 Portugal
The Portugal bench is loading with talent and we see a couple of changes. Wolves midfielder Joao Moutinho and AC Milan forward Rafael Leao are on, with Goncalo Guedes and Matheus Nunes the men replaced.
Liverpool forward Diogo Jota is another option if needed later on.
Post update
Republic of Ireland 0-0 Portugal
The hosts have a free-kick in a good position close to the right touchline. It is swung in by Jamie McGrath and Shane Duffy attacks it, but a foul from John Egan gives away a free-kick.
Josh Cullen soon after curls a low shot from the edge of the box but it's easy for Rui Patricio. Sticking your laces through it may have been the better option there.
Croatia set for Russia showdown
Croatia will face Russia in a decider for Group H top spot on Sunday.
Lovro Majer has put the Croats 5-1 up in Malta, leaving them two points adrift of leaders Russia ahead of the finale.
We're under way and Chiedozie Ogbene is brought down within seconds by Portugal's Joao Palhinha. The hosts have a free-kick 30 yards out, but opt to play it wide instead of shooting at goal, disappointing some of the Aviva Stadium faithful.
Post update
Republic of Ireland 0-0 Portugal
A draw for Portugal would still take them top of Group A, but only on goal difference ahead of Serbia, who they entertain in the group decider on Sunday.
But if Portugal were to lose, then they would need to beat Serbia at the weekend to qualify for Qatar 2022 and anything else would take them into the play-off phase.
Get Involved
#bbcfootball
United We Talk: Ireland holding Portugal to a 0-0 at half time! Plus Ireland have had some decent chances! Not bad indeed!
Live Reporting
Michael Emons
All times stated are UK
Post update
Republic of Ireland 0-0 Portugal
Desperate defending from Portugal as Matt Doherty's effort is charged down by Joao Moutinho.
Can the Republic get a winner?
Post update
Republic of Ireland 0-0 Portugal
Rafael Leao only came on in the 56th minute, but he's replaced in the 83rd minute as Portugal looks to solidify their defence after that Pepe red card.
Ex-Southampton man Jose Fonte, now at French side Lille, is the man on, with Leao replaced.
RED CARD - Pepe (Portugal)
Republic of Ireland 0-0 Portugal
He got booked for dissent 10 minutes earlier, and now Pepe has seen red. He catches Callum Robinson in the face with a stray elbow, and that's a second yellow and Portugal are down to 10.
A real chance for the Republic now to win this.
Post update
Republic of Ireland 0-0 Portugal
That Enda Stevens miss is his last action as he and Jeff Hendrick go off, with James McClean and Conor Hourihane coming on.
Ronaldo, to the home fans' concern, is seeing more of the ball now and has just curled one wide. Just over 10 minutes plus injury time to go.
Seven for Croatia
Anything you can do....
Russia thrashed Cyprus 6-0 earlier, so Group H rivals Croatia have responded by hitting seven against Malta. It's 7-1 now.
Sunday's showdown for top spot between Russia and Croatia is going to be a cracker.
Post update
Republic of Ireland 0-0 Portugal
Some more changes for Portugal. The extremely quiet Bruno Fernandes is off, as is Andre Silva, with Joao Felix and Renato Sanches on.
Moments later the hosts have a chance but Enda Stevens is not the man you want in the situation and he balloons it over the bar after being played in by Chiedozie Ogbene.
Post update
Republic of Ireland 0-0 Portugal
Pepe is shown a yellow for dissent after a clear handball, but the Republic waste the free-kick.
Post update
Republic of Ireland 0-0 Portugal
A booking for Danilo, who is completely done for pace by a sprinting Chiedozie Ogbene down the right flank.
Cynical from Danilo and a deserved yellow.
Post update
Republic of Ireland 0-0 Portugal
Nearly, so nearly for Ronaldo. A cross comes in from the left and he gets above Jeff Hendrick with a glancing header.
Goalkeeper Gavin Bazunu is panicking and at full stretch, but luckily for him, Ronaldo's header is just wide.
Moments afterwards, someone runs on to the pitch aiming for Ronaldo, but the intruder is quickly grabbed by security before getting anywhere near the Manchester United man.
Post update
Republic of Ireland 0-0 Portugal
It's been an excellent defensive performance so far from the Republic. Shane Duffy, in his 50th appearance, shows his strength to shield the ball behind under pressure from substitute Rafael Leao.
Cristiano Ronaldo and Bruno Fernandes have been very, very quiet so far. But we all saw what happened in the first match between these two late on.
Goals galore
Andrek Kramaric now has Croatia 6-1 ahead in Malta, while Leroy Sane puts Germany 5-0 ahead against 10-man Liechtenstein.
SUBSTITUTION
Republic of Ireland 0-0 Portugal (19:45 GMT)
A change for the Republic with Norwich striker Adam Idah on for Jamie McGrath.
Post update
Republic of Ireland 0-0 Portugal
Matt Doherty, close to the dead ball line, manages to squeeze out a cross but Rui Patricio is off his line to dominate the area and end the attack.
SUBSTITUTIONS
Republic of Ireland 0-0 Portugal
The Portugal bench is loading with talent and we see a couple of changes. Wolves midfielder Joao Moutinho and AC Milan forward Rafael Leao are on, with Goncalo Guedes and Matheus Nunes the men replaced.
Liverpool forward Diogo Jota is another option if needed later on.
Post update
Republic of Ireland 0-0 Portugal
The hosts have a free-kick in a good position close to the right touchline. It is swung in by Jamie McGrath and Shane Duffy attacks it, but a foul from John Egan gives away a free-kick.
Josh Cullen soon after curls a low shot from the edge of the box but it's easy for Rui Patricio. Sticking your laces through it may have been the better option there.
Croatia set for Russia showdown
Croatia will face Russia in a decider for Group H top spot on Sunday.
Lovro Majer has put the Croats 5-1 up in Malta, leaving them two points adrift of leaders Russia ahead of the finale.
Post update
Republic of Ireland 0-0 Portugal
Post update
Republic of Ireland 0-0 Portugal
We're under way and Chiedozie Ogbene is brought down within seconds by Portugal's Joao Palhinha. The hosts have a free-kick 30 yards out, but opt to play it wide instead of shooting at goal, disappointing some of the Aviva Stadium faithful.
Post update
Republic of Ireland 0-0 Portugal
A draw for Portugal would still take them top of Group A, but only on goal difference ahead of Serbia, who they entertain in the group decider on Sunday.
But if Portugal were to lose, then they would need to beat Serbia at the weekend to qualify for Qatar 2022 and anything else would take them into the play-off phase.
Get Involved
#bbcfootball
United We Talk: Ireland holding Portugal to a 0-0 at half time! Plus Ireland have had some decent chances! Not bad indeed!