Andy Murray thrashed Andrey Rublev to reach the Australian Open third round but the Scot endured an injury scare after twisting his right ankle, while Dan Evans upset caused a huge shock by defeating Marin CIlic.
Murray's foot gave way at the start of the third set on Rod Laver Arena and while he was still able to see out his 6-3 6-0 6-2 victory, he clearly remained in some discomfort.
The British number one chose not to request any medication from the tournament physio but soon after told his box, "my foot is killing me".
Murray will now face American Sam Querrey in round three.
Asked about his ankle in his on-court interview afterwards, Murray said: "It's just a little bit sore, it's not too serious but I definitely rolled it a bit. I'll make sure I get some ice on it.
"I was moving OK at the end which is positive.
"Sometimes if you roll your ankle and it feels bad, you can't put weight on it but I could put weight on it so I'm sure it'll be fine."
Dan Evans sensationally dumped seventh seed Marin Cilic 3-6 7-5 6-3 6-3 in the second round of the Australian Open, while Roger Federer and Stan Wawrinka also progressed to the third round.
Evans scored his first ever top 10 scalp en route to the Sydney International final last week against world number eight Dominic Thiem, but not only is Cilic one place higher than the Austrian, the scale and stage of this triumph gives it far greater significance.
Stan Wawrinka had to save a match point against Evans before winning the US Open in September but this time the British number three was never going to let the opportunity slip.
He was quicker, cleverer and more consistent than Cilic, who at 6ft 6in towered above Evans in stature but was out-thought and out-fought in front of a packed-out crowd on Court Three.
Evans' victory means he has now reached three consecutive grand slam third rounds and continues a remarkable rise that has seen him surge from 319th in the world this time two years ago, to 52nd.
Cilic, a US Open champion in 2014 and now coached by Jonas Bjorkman, once of Andy Murray's team, showed his class in the opening set but Evans helped him on his way as two missed forehands and a double fault gave away a break for 3-0.
Evans had a sniff at 4-2 when he opened up 0-30 but Cilic came back to hold, one whipped crosscourt forehand prompting Evans to comment "too good".
The second set looked to be going a similar way when Cilic created three break points in the first game but Evans dug deep to hold, overcoming a rare foot-fault along the way, albeit with a few mutterings under his breath.
Cilic did break soon after but Evans was not deterred, responding in kind the very next game with a superb, chiselled backhand pass that drifted inside the line.
At 5-5, a gutsy backhand smash held off two more Cilic break points and now, serving to stay in the set, it was the Croatian's turn to wobble.
Another scintillating backhand pass, this time ripped down the line, gave Evans two set points and he converted at the first time of asking when a Cilic forehand flew long.
Jogging into the change of ends, the momentum was now with the Briton. He broke again at 2-1 in the third, when a review showed Cilic's forehand wide, and served out to love to move a set in front.
Into the fourth and a marathon 15-minute second game, featuring nine deuces, and in which Evans rescued no fewer than eight break points.
As Evans held, pumping his fist, it felt like a fatal blow for Cilic and sure enough Evans broke himself at 3-2 to put victory within his grasp.
Serving to stay in the match at 5-3, Cilic crumbled, a double fault and then a limp forehand into the net handing Evans three match points.
Cilic saved two but not the third as another missed forehand, his 31st of the contest, confirmed Evans' progress after two hours and 58 minutes
Roger Federer dug himself out of a late slump to fend off American qualifier Noah Rubin 7-5 6-3 7-6(3) and enjoy a confidence-building win on the way to the third round of the Australian Open.
On the comeback trail after six months out of the game, a clinical Federer cruised through the opening two sets but fell into a hole in the third against the plucky world number 200.
Federer needed to save two set points on serve at 5-2 down and then came roaring back to take Rubin to a tiebreak.
The Swiss master, seeded 17th, raced to three match points at 6-3 and closed it out on the first with a crunching forehand that Rubin could only parry high and wide as he booked his place in the third round for the 18th time.
"I was just not doing what I was trying to do. I was hoping to play better at times," Federer said afterwards
"I think you can always do better. It's one of those sports like golf, you can always leave frustrated. Like tennis, you can feel: 'I could have always played a little bit better'.
"At the end of the day you have to be happy with what you did, as well. I have to be happy with the little things.
"Sometimes it's not going to be pretty. Sometimes it's just going to be a fight. Today that's what I thought it was for me.
"I guess I was hoping to play better offensive tennis and I struggled with that a little bit at times."
Federer plays 10th seed Tomas Berdych in the next round.
Three-times grand slam winner Stan Wawrinka, who hit 46 winners in a near-flawless display, eased past Steve Johnson, beating the American 6-3 6-4 6-4 in an hour and 51 minutes at Margaret Court Arena.
The Swiss fourth seed will face Italy's Paolo Lorenzi or Serbian Viktor Troicki in the third round.
Germany's Mischa Zverev came back from two sets down to beat American John Isner 6-7(4) 6-7(4) 6-4 7-6(7) 9-7 in four hours and 10 minutes to set up a third round clash with Tunisia's Malek Jaziri.
Czech Republic's 10th seed Tomas Berdych raced into the third round after securing a routine 6-3 7-6(6) 6-2 victory over American Ryan Harrison.
Kei Nishikori swept into the third round of "The Grand Slam of the Asia-Pacific", then lamented the fact the world's most populous continent was still struggling to produce more players capable of ending their grand slam men's singles drought.
The fifth seeded Japanese took just over two hours to beat France's Jeremy Chardy 6-3 6-4 6-3 on Hisense Arena to advance to the third round clash against Slovakia's Lukas Lacko.
The 27-year-old, however, felt unless others followed his example and got out of Asia to train at a younger age then it would struggle to produce grand slam champions.
"I would suggest to (younger Asian players) to go to Europe or U.S"
"I was really lucky that I moved to the U.S., able to hit with all the top players," Nishikori, who moved to Florida as a teenager, told reporters when asked whether the lack of top-class facilities, coaching or player depth was a concern in Asia. "I think that helps a lot to see how they are playing.
"I realised that when I was young and it was a really big step for me.
"I would suggest to (younger Asian players) to go to Europe or U.S. ... when you are junior or when you are really young."
Nishikori used those experiences to become the second Asian man after Thailand's Paradorn Srichaphan to make the top-10 and appears to be Asia's best chance of clinching their first men's grand slam title, having already lost the 2014 U.S. Open final to Croatia's Marin Cilic.
There is, however, daylight between the quietly spoken right hander and the rest of the men's Asian field. Only three others, Taiwan's Lu Yen-hsun (60), Kazakhstan's Mikhail Kukushkin (98) and Japan's Yoshihito Nishioka (99) are currently in the top-100.
