Top seed John Isner and second-seeded Kevin Anderson set up an Atlanta Open final billed as the tallest in ATP tour history with semi-final triumphs on Saturday.
Isner fired 21 aces in a 6-4, 4-6, 7-6 (7/5) victory over Australian veteran Lleyton Hewitt, while South Africa's Anderson saved two set points in the 12th game of the second frame to force the tiebreaker en route to a 6-3, 7-6 (7/3) victory over Ryan Harrison.
In a rivalry that dates back to their US university days, the 2.06 metre tall Isner and 2.03m tall Anderson have met eight times previously, but never in a final. Isner has won five of those meetings, most recently in the quarter-finals at Delray Beach this year.
"John's very tricky to play. Obviously he's got one of the best serves probably in the history of the game, and he really uses it well," said Anderson, another big server who fired 14 aces past Harrison.
Isner, a two-time Atlanta runner-up seeking his seventh career ATP crown, improved to 4-2 against Hewitt and avenged two losses to the Aussie this year -- in the second round at Indian Wells and earlier this month in the semi-finals at Newport.
"I thought I played very well," Isner said. "It's a case where I'm getting more comfortable, now that it's my third match out there. I was able to go for my shots more in this match than I was in my previous matches."
In the third set, Isner went down triple break point in the seventh game but rescued them all with service winners and held.
Hewitt forced another break point in the ninth game but Isner saved it with a serve and volley winner and held for a 5-4 edge on the way to the tie-breaker.
Isner, with the ATP's most tie-breaker wins this year at 23-6 and wins in both of his prior tie-breakers against Hewitt, opened with a 140-mph ace and ripped a forehand winner for a 2-0 lead.
Hewitt fell and Isner hit an easy backhand for a 3-0 advantage but the Aussie, who entered 5-5 in tie-breaks this year, swatted a cross-court forehand winner but then netted a forehand to hand Isner a 4-1 lead.
Hewitt fought back to level at 4-4 when Isner netted a backhand volley. The American answered with his final ace only to have Hewitt respond with a forehand volley winner for 5-5.
Isner reached match point with a backhand volley winner and hit a service winner to take the victory after two hours and 23 minutes.
"I wanted to play that point aggressively and I did," Isner said of the volley that gave him match point. "I hit a fantastic volley. It was a huge point."