Federer in the match when he was on the receiving end started to get annoyed; he was given a code violation for an obscenity. He said that it was simply frustration coming out from his end.
"Honestly, to be frustrated at one point, I think it's normal," he said. "I found it a bit tough. It's not like I'm known to throw around words and whatever. It's not like the whole stadium heard it either."
He added on dealing Sandgren the killer blow in his comeback that it will hurt on his end as he has been in similar matches before in his illustrious career.
"I feel a bit bad in a way because I didn't feel like he did anything really wrong," Federer said afterwards.
"It's just luck at some point. I've been on the other side, as well. These ones just sting, and they hurt. But I could have blinked at the wrong time and shanked. That would have been it."
Federer spoke on his chances going forwards; he said that for him his mindset has been not dwell on matches after they've happened and put it behind him. As well as saying how he feels after this specific match.
"I can get through a match like this, through a match like Millman, yeah, you do believe," said Federer.
"I always believe till it's actually over, never before."
"I didn't feel like I wasted too much emotional energy out there today because I came to terms quickly that things weren't exactly the way I wanted them to be," he added.
"Instead of dwelling over them, I felt like I'll just play with it, see what can be done, see if he can put me away or not. When I got to the fifth set, I was like, 'I don't feel physically exhausted like against Millman.' I recovered very well from that match. I'm also hopeful because I feel like I didn't get spent completely today.
"It really depends sometimes how you're feeling inside, how much it takes away from you. But I must say I feel pretty good right now."
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