Roger Federer was unable to contain his laughter as his Swiss compatriot Belinda Bencic suffered a slip of the tongue following their doubles appearance at the Hopman Cup in Perth on Wednesday.Federer and Bencic were in action against American duo Serena Williams and Francis Tiafoe in one of the season's first events ahead of the Australian Open.The Swiss duo took won the first set, played over four games, 4-2, before they went on to triumph in the second 4-3 following on from a tie-break. But it was after the match that Bencic had a slip of the tongue, before being asked to clarify her comments by Australian host, the former doubles player, Todd Woodbridge."It was very difficult but I'm very happy Roger motivated me in the locker room," the 21-year-old said.'No! Not the locker room, in the gym I meant ... in front of the locker room," as Bencic tried to salvage the situation.Meanwhile, Federer couldn't help but laugh at the messy situation his doubles partner had managed to get herself into - see below.

The 37-year-old veteran is aiming for his third straight Grand Slam title Down Under, which gets underway in the coming weeks.

But he admits he might need to have some luck on his side to emerge victorious in Melbourne.

"I think with my age people know that if I did something extraordinary that would be amazing," Federer said.

"If that didn't happen, maybe it's logical you can't produce that tennis every year. You also maybe need a bit of luck, and the draw to fall your way.

"A lot of things need to happen to win any slam. I hope that again it will be the start of a great season for me because the last two seasons have been crazy good for me."

"I've been very happy with how the off-season went," he added.

"The last three or four weeks have been very intense. I'm very excited and motivated for this next season."