Luxembourg boss Luc Holtz says his players do not fear the Republic of Ireland.
His side are no longer European minnows, beating Cyprus and Montenegro in the recent Nations League and sitting in the top 100 in the Fifa world rankings.
"We have great respect for the Irish team. We have respect, but we have no fear for tomorrow," said Holtz.
"We know that we have made a lot of progress in recent years so the confidence is OK.
"We have to work hard - every match, we have to work hard - and the solidarity of the team is the key for success."
Republic of Ireland boss Stephen Kenny has refused to call this game must-win.
"It depends on your grasp of mathematics, but anything is possible," he said.
"It's important that we win the game. We want to win the game. Must-win - what
is that? Is it an adjective? What does must-win mean?
"We played very well the other day and were disappointed to lose. We want to
win the game against Luxembourg and we will try everything we can."
Post update
In the other games already played Turkey beat Norway 3-0, Russia defeated Slovenia 2-1, Montenegro saw off Gibraltar 4-1 and Belarus beat Estonia 4-2.
Post update
Elsewhere, Real Madrid's Luka Modric became Croatia's most-capped player as his side beat Group H rivals Cyprus 1-0 in their World Cup qualifier.
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Dutch hope for fans experiment success
Netherlands 2-0 Latvia
Matthew Kenyon
BBC World Service in Amsterdam
ReutersCopyright: Reuters
The 55,000-capacity Cruijff Arena housed 5,000 fans for Netherlands' qualifier against Latvia.
Stand-in skipper Gini Wijnaldum of Liverpool sent a message to everyone via one
of the compulsory apps this morning saying how much the players were looking
forward to the experience.
Everyone who is here has had to download a couple of apps, for information and
tracing purposes - and we all have had to show a negative test result taken in
the last 24 hours. I did mine this morning - the (negative) result came through
within 15 minutes.
If the experiment works, this will open the way for fans to come back in some
numbers - maybe even before the end of the domestic season. But this is
also being done with the demand of the European Championship in mind. Uefa want
proof that fans will be able to attend.
Of course, the proof of whether it's a success or otherwise - in a country where
the coronavirus numbers are on their way back up - will only come in the days after
the event. We all have to have another test next week.
The Netherlands won the game 2-0.
What else is going on?
There are three other 19:45 GMT games tonight, and we will be letting you know what is going on in them (to differing degrees).
Serbia - who beat the Irish 3-2 the other day - face Portugal in the group's other game. Belgium face the Czech Republic in Wales' group - and Slovakia face Malta.
Get Involved
#bbcfootball or 81111 on text
Text or tweet in any thoughts you have on tonight's games. If you want.
The Republic of Ireland hand an international debut to 19-year-old goalkeeper Gavin Bazunu, who is on loan at Rochdale from Manchester City.
He replaces Mark Travers in one of three changes from the defeat by Serbia. James Collins, who came off the bench to score in that game, replaces the injured Aaron Connolly, and Jason Knight replaces the benched Jayson Molumby.
Live Reporting
Emlyn Begley
All times stated are UK
'We have respect, but no fear'
Republic of Ireland v Luxembourg (19:45 GMT)
Luxembourg boss Luc Holtz says his players do not fear the Republic of Ireland.
His side are no longer European minnows, beating Cyprus and Montenegro in the recent Nations League and sitting in the top 100 in the Fifa world rankings.
"We have great respect for the Irish team. We have respect, but we have no fear for tomorrow," said Holtz.
"We know that we have made a lot of progress in recent years so the confidence is OK.
"We have to work hard - every match, we have to work hard - and the solidarity of the team is the key for success."
Post update
Wales are playing Mexico in a friendly. There is a separate live text for that if you're interested.
'Must-win - what is that?'
Republic of Ireland v Luxembourg (19:45 GMT)
Republic of Ireland boss Stephen Kenny has refused to call this game must-win.
"It depends on your grasp of mathematics, but anything is possible," he said.
"It's important that we win the game. We want to win the game. Must-win - what is that? Is it an adjective? What does must-win mean?
"We played very well the other day and were disappointed to lose. We want to win the game against Luxembourg and we will try everything we can."
Post update
In the other games already played Turkey beat Norway 3-0, Russia defeated Slovenia 2-1, Montenegro saw off Gibraltar 4-1 and Belarus beat Estonia 4-2.
Post update
Elsewhere, Real Madrid's Luka Modric became Croatia's most-capped player as his side beat Group H rivals Cyprus 1-0 in their World Cup qualifier.
Dutch hope for fans experiment success
Netherlands 2-0 Latvia
Matthew Kenyon
BBC World Service in Amsterdam
The 55,000-capacity Cruijff Arena housed 5,000 fans for Netherlands' qualifier against Latvia.
Stand-in skipper Gini Wijnaldum of Liverpool sent a message to everyone via one of the compulsory apps this morning saying how much the players were looking forward to the experience.
Everyone who is here has had to download a couple of apps, for information and tracing purposes - and we all have had to show a negative test result taken in the last 24 hours. I did mine this morning - the (negative) result came through within 15 minutes.
If the experiment works, this will open the way for fans to come back in some numbers - maybe even before the end of the domestic season. But this is also being done with the demand of the European Championship in mind. Uefa want proof that fans will be able to attend.
Of course, the proof of whether it's a success or otherwise - in a country where the coronavirus numbers are on their way back up - will only come in the days after the event. We all have to have another test next week.
The Netherlands won the game 2-0.
What else is going on?
There are three other 19:45 GMT games tonight, and we will be letting you know what is going on in them (to differing degrees).
Serbia - who beat the Irish 3-2 the other day - face Portugal in the group's other game. Belgium face the Czech Republic in Wales' group - and Slovakia face Malta.
Get Involved
#bbcfootball or 81111 on text
Text or tweet in any thoughts you have on tonight's games. If you want.
Post update
Team news
Republic of Ireland v Luxembourg (19:45 GMT)
The Republic of Ireland hand an international debut to 19-year-old goalkeeper Gavin Bazunu, who is on loan at Rochdale from Manchester City.
He replaces Mark Travers in one of three changes from the defeat by Serbia. James Collins, who came off the bench to score in that game, replaces the injured Aaron Connolly, and Jason Knight replaces the benched Jayson Molumby.
Republic of Ireland: Bazunu, Coleman, O'Shea, Clark, Doherty, Knight, Cullen, Browne, Stevens, Robinson, Collins. Subs: Horgan, Parrott, Christie, Molumby, Brady, Lenihan, McClean, O'Hara, Shane Long, Travers, Duffy, Hendrick.
Luxembourg: Moris, Da Graca, Jans, Chanot, Mahmutovic, Martins Pereira, Rodrigues, Barreiro, Sinani, Olivier Thill, Vincent Thill. Subs: Muratovic, Schon, Fox, Dzogovic, Gerson, Mica Pinto, Skenderovic, Rupil, Bohnert, Deville, Sebastien Thill.
Post update
Republic of Ireland v Luxembourg (19:45 GMT)
The Irish lost their opening qualifier 3-2 to Serbia on Wednesday.
But that marked the end of seven games in a row without scoring.
Today is Stephen Kenny's 10th game in charge. They have yet to win.
Post update
Republic of Ireland v Luxembourg (19:45 GMT)
On Wednesday the Republic of Ireland remembered how to score.
Today they have to remember how to win.
Welcome to live text commentary of the crucial World Cup qualifier with Luxembourg.