Main-draw action at the Phoenix Challenger got off to a roaring start Tuesday as two of the Top-5 seeds were upset in the opening round. Australian Thanasi Kokkinakis ousted Jiri Lehecka before World No. 80 Nuno Borges got past second seed Diego Schwartzman under the lights at the Arizona Tennis Classic.

Fresh off an Indian Wells clash against World No. 2 Carlos Alcaraz, Kokkinakis made the trip to Arizona after falling to the Spaniard. On Tuesday, the 26-year-old won 37 of 45 first serve points to defeat fifth seed Lehecka 7-6(5), 6-4.

“Stoked to get it done,” Kokkinakis said. “He’s going to be a very good player for years to come. He’s explosive, has a lot of firepower, very athletic. He’s playing some great tennis this year, he made the quarter-finals at the Australian Open. I had to kind of weather the storm, the conditions are very slow here. I just tried to stay patient and out grind him.”

Borges stayed consistent from the baseline and punished World No. 38 Schwartzman’s deep court positioning to earn the highest-ranked win of his career and upset the second seed 7-5, 6-3. The Portuguese No. 1, who won last month’s Monterrey Challenger, awaits the winner of Pedro Martinez and Roman Safiullin.

In other main-draw action, fourth seed Alexander Bublik defeated defending Phoenix Challenger champion Denis Kudla 7-6(9), 4-6, 6-2. The Kazakh will next face lucky loser Rinky Hijikata or Chinese star Zhizhen Zhang.