Video: Isner and Nadal to meet in Cincinnati final

Unseeded American John Isner rallied from losing a first-set tiebreaker to upset seventh-seed Juan Martin del Potro in a gruelling Western & Southern Open semi-final on Saturday.

The 22nd-ranked Isner, who beat world number one Novak Djokovic in the quarter-finals on Friday, rose to the challenge again on Saturday downing del Potro in three sets 6-7 7-6 6-3.

Having lost the first set on the tiebreak, Isner was in danger of losing in straight sets as the world number seven served for the match at 5-3 in the second.

But Del Potro double-faulted at match point.

Isner took his chance, first forcing a tiebreak before going on to take the third set with relative ease to reach the second Masters 1000 final of his career.

In the final, he’ll play fourth-seed Rafael Nadal, who overcame sixth-seeded Tomas Berdych, 7-5, 7-6 (4) to reach the final for the first time in his fifth appearance.

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.