LONDON—An emotional and sometimes irritated Roger Federer says he is not taking any positives out of losing to Novak Djokovic twice in the past four days. Djokovic beat Federer in the Paris Masters semifinals and in their opening round-robin match at the ATP World Tour Finals.

“Great, we’re positive,” he said sarcastically. “It was great to win two sets off Novak, and losing four. Losing a match, it’s really exciting. But I don’t know what to tell you. The season’s not done yet. Let’s talk about this stuff in hopefully four matches.”

Federer also mentioned that his troubles are more mental than physical.

“I think at this point it’s very mental, just making sure I don’t get too negative on myself because of the loss today,” he said. “It was against Novak after all. It’s not against some journeyman. So I feel like it was very close, but then again didn’t make it. It’s a positive that it was three sets. Don’t really care. But I just have to make sure I stay positive right now in my mind, which I am.

"And I’m looking forward to the next matches. And I’m happy how I recovered from Paris. That was really key for me to see today how I was going to feel  Maybe I did have some ups and downs, but that’s more towards the season I played and more I think a lot of matches. Then I just got to play my game. It does remain indoors. So I think I have to just make sure I take it to my opponents rather than trying to make the plays too often, what I was trying to do today … But obviously it’s been a tough season overall. So I guess I’m just rattled at times, with my level of play consistently.”