Top-seeded John Isner has been eliminated in the second round of the ATP Tour’s ASB Classic, losing 7-6 (7-3), 7-6 (7-5) to fellow American Taylor Fritz.

On a good day for young Americans, Tennys Sandgren also beat third-seeded Marco Checchinato of Italy 6-3, 6-3.

Isner’s defeat was another blow to a tournament already deprived of star power by the withdrawals of Gael Monfils, Roberto Bautista Agut and Tomas Berdych and the first-round losses of Hyeon Chung and Denis Shapovalov.

Fritz had lost to Isner in their two previous meetings but prevailed Wednesday in the face of Isner’s barrage of 26 aces.

The 21-year-old Fritz, ranked 50th, managed to beat his 10th-ranked compatriot for the first time by winning a handful of key points in both tiebreaks.

“It feels great. John’s beaten me twice before and it was close,” he said.

“I really wanted to get the win on him and I knew I could. We had a lot of close points and it just feels really good to get through that.”

Fritz won more tiebreaks in 2018 than any other player and he put that ability to good use Wednesday to claim his fourth win over a top-20 player.

“I like to think that one of the strengths of my game is playing under pressure and playing the big moments well,” he said.

“More often than not in the matches I lose that’s where I get let down.

“So I’m happy to start every year and today as well playing well under pressure and handling those big moments well.”