"But I've found out that I need to have the game B in the end of the day".
"I'm going to recover for tomorrow", he added.
Novak Djokovic is one victory away from the only ATP Masters title he has yet to win, the Western & Southern Open.
"It's great to be back in the finals, against Novak in particular", Federer said.
Despite facing an opponent who had to finish, and win, his third-round matchup earlier in the day, the Canadian couldn't fight off a pumped-up Djokovic in the deciding set.
But after the pause, the pair came back out, with Federer finally securing the first break of the match on his seventh chance to take a 4-2 lead over his longtime rival. "I've now got a hard final against a tough opponent".
Djokovic had to work for more than two and a half hours to overcome Cilic, the 2016 champion in the combined WTA and ATP event. He then dismissed Leonardo Mayer 6-1 7-6 to set up a quarterfinal clash with his compatriot Stan Wawrinka in the quarterfinals, with Federer having to pull double duty thanks to a rain delay.
Federer won their only previous final here in 2015 in straight sets.
"I never felt, so to say, embarrassed to say that I'm someone who makes mistakes, and I'm not proud when I break the racquet, especially I know there are kids around and watching, and I'm not proud of it, but sometimes it's just - it's too strong, and you let it out", he said. Djokovic is trying to become the first to win all nine events since the series started in 1990.
The 20-time Grand Slam champion has won all of his last seven finals in Cincinnati, including three at Djokovic's expense, and will hope to maintain his ideal record.
"I've played five finals here, so that's pretty OK", Djokovic said.
In the women's draw, Dutch outsider Kiki Bertens reached her third final of the season as she wore down a tiring Petra Kvitova 3-6, 6-4, 6-2. I had a lot of trouble with my knee, so I didn't play the full year.
Djokovic soon returned to form in the decider, winning 90% of his first serve points, and clinching the victory on his second match point.
No. 2 Caroline Wozniacki retired from her match Wednesday night because of an injured left knee, her second straight disappointing exit from a tournament.
Djokovic won just eight points on his return in the first set of the semi-final, but breaking Cilic's serve in the third game before twice saving break point gave him the momentum to take the early advantage. "It was a tough match, but I'm so glad to be in the final".
Halep broke in the final game to move through as Sabalenka volleyed long on a second match point after 76 minutes.