(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. (Reporting by Gene Cherry in Raleigh, North Carolina, additional reporting by Andrew Both, editing by Pritha Sarkar)<doc-sep>World number 3 and defending Citi Open champion Alexander Zverev is through to the semi-final following a 3-6 6-1 6-4 win over Kei Nishikori in an hour and 45 minutes, beating the Japanese for the second time in a row at this event. This was the 39th win of the season for Sascha and his seventh semi-final of the season, the first since Rome, also becoming the Tour leader in the number of wins in 2018 in front of Dominic Thiem. The German seized control after losing the opening set and he managed to bring the match home after another rain delay that moved the match between Denis Kudla and Andrey Rublev to Saturday. Sascha served at 75% and he lost 16 points in 13 service games, suffering two breaks from as many chances he gave to Kei but erasing that deficit with a solid performance on the return. Nishikori lost 43% of the points in his games, struggling on both the first and second serve to face 11 break points, getting broken four times to end his run in the quarters. The German had 18 winners and 22 errors while the Japanese never found his rhythm after the opening set, hitting 13 winners but also 30 errors, missing mostly from his backhand side. The opening set was decided in the sixth game when Kei forced an error from his rival to move 4-2 up, serving for the set in game nine. Zverev created two break points but Nishikori saved them with a forced error and a service winner, closing the opener with another unreturned serve in 30 minutes. Sascha took charge in set number two, dropping three points on serve and keeping the pressure on Kei who couldn't deal with it. Nishikori saved four break points in game two but Zverev found the way to break him two games later when he forced an error from his opponent. The German was untouchable in his games and he broke once again in game six with a backhand down the line winner, serving for the set in the following game. He fired four service winners to grab the set 6-1 and he was now the favorite to reach the semi-final. Sascha broke at love in game five of the decider and the match was halted due to rain until 8 pm when the German held with a service winner for a 4-2. Nothing worked in Kei's favor and he got broken again in game seven after failing to control a volley, allowing Sascha to serve for the triumph. Out of sudden, Nishikori broke at love to reduce the deficit to 5-4 but Zverev sealed the deal with a good hold in game 10 to book his place in the semis. Quarter-final results: ↓ SHOW RESULTS ↓ [1]Alexander Zverev (GER) vs [7]Kei Nishikori (JPN) 3-6 6-1 6-4 [10]Stefanos Tsitsipas (GRE) vs [3]David Goffin (BEL) 6-3 6-4 Alex de Minaur (AUS) vs Andy Murray (GBR) W/O ALSO READ: August 3, 2004: Roger Federer suffers unexpected loss after a great run<doc-sep>
World number 3 and defending Washington champion Alexander Zverev is the first player with 40 ATP wins in 2018, advancing to his fifth ATP final of the season after a 6-2 6-4 win over the fellow U21 star Stefanos Tsitsipas in an hour and 28 minutes. These two have never played before, even on the junior level, and Zverev confirmed the status of the pre-match favorite after a rock solid performance on his serve, dropping 13 points in eight service games and never facing a break point. Tsitsipas played another impressive tournament and will reach the Top 30 on Monday but he stood no chance against Sascha today, losing 45% of the points in his games and suffering three breaks from seven opportunities he gave to the German. Zverev had 23 winners and 18 unforced errors while Tsitsipas hit 15 winners with 22 errors, unable to impose his shots or to move Sascha from the comfort zone. It was all about Zverev in the opening set and he drew first blood in game three when Stefanos hit a double fault to give his serve away. A forehand winner at 3-1 gave Zverev another break and he sealed the set with an ace in game eight after 34 minutes. Stefanos raised his level in set number two and nothing could separate them in the first eight games, reaching 4-4 easily and marching towards a tie break. Instead of that, the Greek lost the ground in game nine, losing serve after nine deuces and four break points for Zverev who grabbed the break after a forehand error from Stefanos, 15 minutes since the start of the game. Four service winners delivered an easy hold for Sascha in game 10 and he will now face Alex de Minaur or Andrey Rublev in the title match on Sunday. Saturday's results: ↓ SHOW RESULTS ↓ Quarter-final result: [16]Andrey Rublev (RUS) vs Denis Kudla (USA) 6-1 6-4 Semi-final result: [1]Alexander Zverev (GER) vs [10]Stefanos Tsitsipas (GRE) 6-2 6-4 ALSO READ: Jennifer Capriati - the 14-year-old girl who conquered the world (Part I)