Speaking to the Los Angeles Times, Pete Sampras says he still hasn't shrugged off Andre Agassi's imitation of him as a bad tipper during the Hit for Haiti exhibition on Friday night.
"Mostly, this just bums me out," Sampras told the newspaper. "It makes our relationship uncomfortable now... It saddens me.
"We've done this before, the imitating each other. He usually just sticks out his tongue at me."
The 14-time Grand Slam champion could not say whether the incident would have a long-term effect on their relationship. "Time will tell," said Sampras. "I like Andre. I always had great respect for his game. What happened is regrettable. It is a very awkward situation.
In an interview with ESPN's Rick Reilly earlier in the week, Agassi said he had texted Sampras asking if he could apologize personally but had not yet received a response.