After the celebrity pair's first-round Wimbledon win over Andreas Mies and Alexa Guarachi last week, Murray tweeted: "Well that was fun... #SerAndy"

But Williams told reporters on Monday she was not sure about SerAndy: "I like Murena. My vote is still for Murena," she said.

Williams is happy there is so much attention on the partnership at Wimbledon where Murray is a local hero after twice winning the men's title.

"It's great. I definitely have been really enjoying the mixed doubles, this pairing. Quite frankly, it's pretty cool. It's pretty awesome."

The 37-year-old American, who is still on course for her 24th Grand Slam singles title after beating Carla Suarez Navarro 6-2 6-2 to reach the quarter-finals, said she was also pleased she had learned to avoid hitting the ball on the wrong side of the net.

She dropped a point against the Spaniard after leaning over to put away a volley.

"I definitely didn't realise it was a rule," said Williams, who has been playing Grand Slam tennis for 21 years.

"I feel like I may have done that before like in doubles, so...I'm glad, because I don't want to make that mistake in our Murena doubles match."

The celebrity pair meet 14th seeds Fabrice Martin and Raquel Atawo in the mixed doubles second round.