Roger Federer cut a frustrated figure throughout his clash with Alexander Zverev, despite booking his spot in the semi-finals.
The 19-time Grand Slam champion was pushed to the limit by the 20-year-old German and could be seen muttering at himself with irritation as he attempted to avenge his Montreal Masters final defeat.
Zverev is one of just four men to beat the Swiss in 2017 and Federer was determined to not allow him to become the only player to win more than one match against him this season.
And he explained why he was losing his cool, as he attempted to find his best tennis.
‘I felt like I lost my ways a little bit in the second set, especially being up a set and a break,’ he said after the 7-6 (8-6) 5-7 6-2 win.
‘But because I did so much work in defence, I forgot how to play normal offence. Like I said, it was still early days in the tournament.
‘I just think it’s hard for anybody right now to hit winners off the ground. We see it. It’s tough. With [Dominic] Thiem, [Grigor] Dimitrov, they struggled. Rafa [Nadal] and David [Goffin]. It’s not so simple just to stretch the lead all the time.
‘I think the court, because it’s a bit faster, it just keeps guys closer to one another. You have to be extremely careful on your service games.
‘You could be up 30-Love, you lose, I don’t know, a relaxed point to where you think, Let me quickly sneak in a quick point to go 40-Love. You lose that point, double-fault, 30-All. All of a sudden you’re in trouble. All he needs is one good return and things are terrible.
‘I think that was bothering me that I wasn’t able to play better, but at the same time I was happy I was in the lead in some ways.
‘So I just think still fighting those early stages of rhythm problems I’m feeling from the baseline. But, look, I’m really hoping and believe I’m going to play better in my third match.’