MASON, Ohio — John Isner's absence from the ATP top 20 will be brief.
The 6-foot-10 American made sure of that Saturday, rallying to beat seventh-seeded Juan Martin del Potro 6-7 (4), 7-6 (9), 6-3 in a grueling Western & Southern Open semifinal.
Isner, who fell from No. 20 to 22 this week, will return to the top 20 after a stimulating Cincinnati run that includes beating three straight top-10 players for the first time in his career while earning his second Masters 1000 series finals appearance and first in Cincinnati. His previous Masters 1000 final appearance was at Indian Wells in 2012.
Isner, in his first appearance in the tournament's semifinals, had been 0-4 against the Argentine. He'll play third-seeded Rafael Nadal, who beat sixth-seeded Tomas Berdych 7-5, 7-6 (4) in the other semifinal to reach the tournament final for the first time in nine appearances.
Nadal extended his personal winning streak against the Czech to 14 matches while improving his overall season record 52-3, including 14-0 on hardcourts. After winning at Montreal last week, the Spaniard will be making back-to-back appearances in hardcourt finals for the first time in his career.
He's 15-1 against top-10 players this season.
Top-ranked Serena Williams also will be making her first career appearance in the event's championship match after ousting defending champion Li Na, 7-5, 7-5, in the first women's semifinal. Williams, seeking her ninth title of the year, advanced when Li double-faulted on match point. Williams improved to 60-3 this season.
Williams will play second-seeded Victoria Azarenka in today's final. Azarenka beat 14th-seeded Jelena Jankovic 4-6, 6-2, 6-3 in a semifinal that featured 23 service breaks in 27 games.
Isner needed 2 hours, 47 minutes to improve to 16-3 since retiring from Wimbledon in the second round because of a left knee injury.