There is no tougher test in tennis right now than beating Serena Williams, according to Andy Murray, whose British peer Heather Watson faces the all-conquering world No. 1 at Wimbledon on Friday.
Williams is looking to complete three-quarters of what would be a second calendar Grand Slam of her career by claiming a sixth Wimbledon title at the All England Club.
Standing in her way is Watson, the 23-year-old who trained and lived at the Nick Bollettieri Tennis Academy in Florida. The world No. 64 is through to the third round at Wimbledon for just the second time in her career.
"Probably the biggest test in tennis right now, I would think," Murray said Thursday about the task facing his compatriot. "I saw a little bit of Serena's match yesterday. She looked extremely motivated from the beginning. In some of the matches at the French Open, it didn't appear that way.
"I don't know if that was nerves or anything. But she looked pretty fired up the other day. So it's going to be an extremely difficult match for Heather.
Murray said that Watson will have the crowd behind her. "She has to try to use that to her advantage, try not to be intimidated," he said. "Just go out there and give it a go.
"I'm not going to go into tactics or anything, but she needs to really go for it, try not to let Serena dictate, and hopefully she can serve well. That will make a big difference."
Watson's previous run to the third round in 2012 saw her nerves get the better of her as she was comfortably beaten 6-0, 6-2 on Centre Court by Agnieszka Radwanska.
Speaking before Serena's second-round 6-4, 6-1 victory over Timea Babos, Watson admitted she would relish the chance to test herself against the American.
"Serena's a great player," Watson said. "She's an amazing athlete, a great champion. She's always the one to watch. She's always the favorite for every tournament she plays. "So I think she's the one to beat in tournaments like this. She's probably the toughest opponent.
"She's obviously a very, very tough opponent. But I feel like in matches like that, you've got a lot to gain, so it's a real positive as well to play her."