Delray Beach, FL (SportsNetwork.com) - Top seed Tommy Haas and former world No. 1 Lleyton Hewitt were both sent packing Wednesday at the Delray Beach Open tennis event.

American qualifier Steve Johnson stunned Haas 6-4, 2-6, 7-6 (7-2) in second- round action on the hardcourts at Delray Beach Tennis Center. Haas titled here in 2006.

Marinko Matosevic, who was the 2012 runner-up here, was leading Hewitt, the No. 8 seed, 7-6 (7-2) when the Australian retired with a right shoulder injury.

Matosevic advanced to his third quarterfinal of the season.

In some other second-round play, fourth-seeded South African native, Delray Beach resident and 2012 champion Kevin Anderson was leading 6-foot-10 Ivo Karlovic 1-0 in the first set when the towering Croat and 2010 runner-up retired with an upset stomach and sixth-seeded Spaniard Feliciano Lopez came from behind to best French fellow left-hander Adrian Mannarino 4-6, 6-4, 6-2. Karlovic was a runner-up in Memphis on Sunday.

The first round concluded Wednesday when hot seventh-seeded Croat Marin Cilic leveled German Benjamin Becker 6-1, 6-3. The surging Cilic titled in Zagreb two weeks ago and was a runner-up in Rotterdam last week.

"Today it was gusty with the wind," said Cilic. "He got a break in the second set, but it was a matter of getting the concentration back and playing well like I did in the first set. Obviously, I'm in good form, my confidence is boosting."