Federer beats Youzhny 6-1 6-7 (3-7) 4-6 6-4 6-2
Rogers and Gavrilova play longest women's match in US Open history
World number one Pliskova beats Gibbs 2-6 6-3 6-4
Seeds Dimitrov and Berdych knocked out, Del Potro through
Day four of US Open at Flushing Meadows
Federer 1-0 Youzhny*
An inside-out forehand gets Federer going but a double fault - something which plagued the world number three in the first round - takes it to 30-30.
No troubles, though - a serve out wide is followed by an ace down the T, and Federer holds first up.
* denotes next server
Federer v Youzhny
Here we go. It'll be Federer to serve first.
Federer v Youzhny
Mikhail Youzhny banged down 11 aces en route to beating Blaz Kavcic and setting up a second-round meeting with Federer.
However, he has a poor record against Federer, having lost all 16 of their previous meetings.
In fact, only David Ferrer has lost more times to the Swiss, with 17 head-to-head defeats.
Youzhny will be looking to avoid equalling that record today...
Image source, Getty ImagesFederer, predictably, gives nothing away when he's asked how he's feeling after his five-set opener against Frances Tiafoe.
"Good, I had a nice hit in Central Park yesterday, which was really fun. The match gave me confidence in my body and my movement.
"There was a lot of kids which was great to see. At one point I looked over and all 20 courts were empty and everyone was watching me - I hope I didn't ruin their practice."
I'm sure they wouldn't have minded if you did, Rog...
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Federer v Youzhny
A gargantuan noise greets Federer as he makes his way out behind Youzhny. Fed's in red and white - Youzhny is looking much more colourful, albeit in a muted way.
Federer v Youzhny
Youzhny, master of understatement, just said "it's not easy" facing Federer. A quick glance at their head-to-head record hints at that.
Image source, Getty ImagesFederer v Youzhny
It's been an almighty year for Federer, adding another Wimbledon and Melbourne title to his ever-expanding trophy cabinent.
But even the GOAT suffers from niggles like us mere mortals.
A back injury interrupted his US Open build-up and he was taken to five sets by teenager Frances Tiafoe on Tuesday, with Fed coughing up 56 unforced errors in a mixed performance.
Image source, Getty ImagesFederer v Youzhny
Imagine if you're just talking a casual walk through Central Park and you happen upon this...
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Would you be tempted to pick up a racquet and have a quick hit?
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Federer v Youzhny
Up next? One Roger Federer.
Image source, AFP
Piers Newbery
BBC Sport at Flushing Meadows
Hugs and high-fives all round on Court Six as Jamie Murray and Bruno Soares sneak through a tie-break for a straight-set win over Julian Knowle and Alexander Peya. Murray swats away a forehand volley on match point, Judy Murray looks thrilled in the stands, and Soares poses for a couple of selfies with fans as the happy team depart to the locker room. Job done.
It's interesting to hear the world number one admit she was feeling the pressure in her third-round victory.
Nicole Gibbs definitely made it tough for her.
The American actually hit more winners than Pliskova in the end - 32 compared to 29 - but it was those big points at the end which hurt the world number 127.
Ka Pliskova 2-6 6-3 6-4 Gibbs
Karolina Pliskova, speaking following her 2-6 6-3 6-4 victory over Nicole Gibbs: "I think in the second set I improved a little bit. I started to serve much better.
"I think she was playing really aggressively from the baseline and I didn't have many chances to play my game.
"In some matches you need the serve more than normal. I didn't feel my game from the baseline was dead good today.
"I think it's easier for people to play me now than for me to play them - I feel the pressure now. Everyone is playing their best tennis against me and I felt it today."
Image source, Rex Features
Mike Dickson
Daily Mail tennis correspondent on BBC Radio 5 live sports extra at Flushing Meadows
The game where she broke Gibbs - you felt Gibbs got anxious and got too pro-active when she didn't need to be. She lost her serve to love and, in fairness to Pliskova, she served it out very professionally.
Gigi Salmon
BBC Radio 5 live sports extra commentator at Flushing Meadows
It's been a battle for Pliskova. She's not had things her own way. It took her a while to get going but she got over the finish line.
Image source, Reuters
Ka Pliskova 2-6 6-3 6-4 Gibbs
It wasn't easy but world number one Karolina Pliskova survives to reach round three.
Nicole Gibbs was outstanding in the first set but just faded at the end of the second and in the decider.
Karolina Pliskova will be relieved she did. The Czech was not at her best but found a way.
Image source, AFP*Ka Pliskova 2-6 6-3 5-4 Gibbs
Three big serves bring up three match points for world number one Karolina Pliskova...
Ka Pliskova 2-6 6-3 5-4 Gibbs
Can the New York crowd spark the American back into life?
They do their best to support her as Gibbs comes to the net to finish a point and take her to 30-15.
Two loose errors from Pliskova. The fans love it. Gibbs pumps her fists. She stays in it but I think Pliskova already had the following game on her mind there.
Rublev 7-5 7-6 (7-3) Dimitrov
Now then.
In both sets, Dimitrov has led with a break. And he's lost both sets.
A double fault from the Bulgarian hands Andrey Rublev a set point, and he hammers home his advantage with a slapped forehand down the line.
Ka Pliskova 2-6 6-3 5-3 Gibbs*
11 points in a row now for Karolina Pliskova and suddenly this game looks done. Gibbs' racquet hits the court and she looks lost.
The American stops the run on points against her but then goes long with a lob.
Pliskova holds and is a game away from the third round...
*Ka Pliskova 2-6 6-3 4-3 Gibbs
And now pressure straight onto Gibbs.
After four quick points to win the previous game, Pliskova races to 0-40 to give her three break points.
She only needs one!
World number one Karolina Pliskova has had to battle but now she leads with a break in the decider. Ashe falls silent.
Image source, AFP