(Reuters) - Champion Alexander Zverev cruised into the final of the Citi Open with a 6-2 6-4 victory over Greece's Stefanos Tsitsipas in Washington on Saturday.
World number three Zverev needed 87 minutes to win his 40th match of the year.
The German dropped only one point on his first serve and took advantage of the 10th seeded Greek's poor serving in the first set.
The second set was tighter. Tsitsipas, serving better, landed 65 percent of first serves and used that to moved closer to the baseline and prohibit Zverev from attacking from the first ball.
But in a 24-point game at 4-4, Zverev dived to earn one of six game points and on his fourth break point of the game, made a return off a deep second serve. Tsitsipas hit a forehand into the net to concede the deciding break.
“I saw he was getting a little bit tired, Zverev told Tennis Channel. "I think the heat helped me in this case a little bit. I saw him hitting himself (he smashed his palm against forehead five times at a changeover).”
Zverev will seek his third title of 2018 when he plays either Russia's Andrey Rublev or Australia's Alex de Minaur in Sunday's final.
Rublev and de Minaur were scheduled to play their semi-final later on Saturday.
The 16th seeded Rublev started his day by defeating American Denis Kudla 6-1 6-4 in a delayed quarter-final match.
Now on a nine-match Citi Open winning streak, Zverev chided officials for scheduling his semi-final in the afternoon after playing night matches all week.
“You play the whole week during the night and then all of a sudden on semi-finals day let’s play at 2 o’clock," the German said. "I’m not so sure of that idea.
"The semi-finals you want to play with the same conditions, with the same rhythm you had and all of a sudden you’ve got to go out there with the hottest weather all week.
"We’ve been going to sleep at 3:30-4 am and now all of a sudden we have to wake up at 10 o’clock and get ready to play.”
He said the only day match he played last year was the final.