The heat took its toll Thursday at the Atlanta Tennis Championships.

Johns Creek paramedics treated four people at the tournament at the Atlanta Athletic Club because of the warm temperatures. The heat index reached 100 degrees under sunny skies with little breeze.

Three of the four were taken to Emory Johns Creek Hospital with heat exhaustion or similar conditions, Johns Creek city public-information officer Rosemary Taylor said. The fourth was a tournament official who refused to be transported.

While the first three days of the tournament have been similarly hot, those four were the first to require such attention, Taylor said.

Players felt it, too.

"I think it kind of goes in waves," said Andy Roddick, a winner over Rajeev Ram in the first match of the day. "When you get in the heat, you get in the middle of the day. I've felt better during tennis matches, that's for sure."

Thursday's results

Lukas Lacko delivered the upset of the tournament, knocking out former world No. 1 Lleyton Hewitt in a second-round match Thursday night 6-4, 6-2. Hewitt's errant service game (38 percent on first serves) allowed Lacko to break the No. 3 seed five times. Lacko will play Kevin Anderson in a noon quarterfinal Friday.

"The result is one of the best of my career," said Lacko, 22.

Hewitt, ranked No. 30 in the world, said he was hobbled by an injury that he wouldn’t specify.

Atlantan Donald Young fell in the second round to Anderson 7-5, 6-3.

"I wanted to do well here, for sure, especially against someone I've beaten a couple times," Young said. "I feel like it was definitely a winnable match."

Friday's slate

Georgia grad John Isner's quarterfinal match with Michael Russell will highlight the early session Friday. Theirs will be the third of three afternoon matches on the stadium court. The match will start no earlier than 4 p.m. In the evening, Roddick will play Xavier Malisse at 7 p.m. in another quarterfinal, followed by Americans Taylor Dent and Mardy Fish.

Tennis town

Atlanta is in the running to be named "America's Best Tennis City" by the U.S. Tennis Association. The winning city, based on voting at www.besttennistown.com, will receive $100,000. The money would go toward funding tennis programs in parks-and-recreation centers in the city of Atlanta.

With more than 50,000 participants, Atlanta has the largest USTA adult and junior leagues in the country. The Atlanta Lawn Tennis Association boasts more than 80,000 members. Deadline for voting is Monday.

Etc.

• Cobb County's Melanie Oudin made an autograph-signing appearance Thursday afternoon. Oudin, who will play the Bank of the West Classic in Stanford, Calif., next week, also took in matches Wednesday. She acknowledged with a smile being jealous of the men's tour having an event in Atlanta.

"It would be great to have a tournament here," she said. "Maybe in the future they'll have one."

• Attendance on Thursday was 3,971, exceeding Wednesday's figure by about 200.