Andre Agassi told ESPN.com he was “out of line” and apologized for poking fun at Pete Sampras during a charity match last week. Longtime rivals Agassi and Sampras were wearing microphones during the match, and the crowd at Indian Wells Tennis Garden in California could hear an exchange that started lighthearted but turned testy. After Sampras and Roger Federer had taken the lead, the American celebrated with a fist bump, prompting Agassi to reply: “You always have to get serious, huh Pete?” Sampras countered: “Okay Andre, I'll joke a little bit. I'm going to imitate you.” He then mimicked Agassi's bow-legged shuffle. In response, Agassi turned his pockets out and said: “I don't have any money. No, wait, I've got a dollar” The back-and-forth continued, Sampras at one point saying: “If that's the way you want to play it”, and Agassi responding: “It's better than being a valet driver and you pulling up.” Both Agassi and Sampras were smiling, but neither showed up at the post-match news conference. “It was out of line,” Agassi told ESPN.com Monday. “It was inappropriate. The night was on fire. We were all having fun. I was trying to be comedic. I only had a split second to make a decision. I went for it and it fell flat. I was trying to get past it, but Pete didn't really let me get past it. He didn't really roll with it. I've texted Pete to ask him if I can apologize in person. The joke fell flat and I'm sorry,” he added. “My hope was that the night was still enjoyable.” Nadal was asked about Sampras and Agassi after his Monday night match. “Everybody told me after the match what's happened, but during the match, you know how fast Americans speak, and I am Spanish. I didn't understand nothing,” he said. He said he felt no tension between them either on or off the court. World No. 1 Roger Federer, however, described the verbal showdown as an “awkward moment” and “a bit unfortunate”. “There was definitely an awkward moment, a bit of a heated moment,” Federer told reporters Sunday after beating Romania's Victor Hanescu at the Indian Wells ATP tournament. “It's a bit unfortunate, but that stuff kind of happens. It's a pity if that's what grabs the limelight and not the event itself, you know.” Federer and Sampras overcame Agassi and Rafael Nadal 8-6 in the match to raise money for victims of the Haiti earthquake. Federer felt it had perhaps been a bad idea to have the four players miked up. “You're sitting there and you're thinking: ‘What now?' I can't say. I wish we wouldn't play with the microphones on, to be quite honest,” he said. A capacity crowd of 16,100 filled the stadium for the Hit for Haiti fundraising exhibition Friday night. The event helped raise $1 million to aid relief efforts in the earthquake