Serena Williams prides herself on her fashion sense and that's an important trait to have at Wimbledon, what with its strict dress code and all.

The tennis legend has her own clothing line and has never been afraid to wear what she wants, like the all black, skin-tight catsuit at last year's French Open.

But Williams took accessorising to an unnecessary level in her highly-anticipated mixed doubles debut with Scottish hero Andy Murray as he made a triumphant return to Wimbledon after hip surgery in their 6-4 6-1 win over Andreas Mies and Alexa Guarachi.

The American great didn't fall foul of the All England Club's fashion police but she sure provided a laughable moment for those watching her and Murray on Centre Court when she played the first two points of the match still wearing her accreditation around her neck.

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She realised her oversight midway through the opening game and removed her lanyard and pass, but she couldn't escape the ever-present eyes of social media.

Williams' blockbuster pairing with Murray thrilled the tennis world when it was announced and after having their round one match postponed, they duo didn't disappoint when promoted to Wimbledon's main stage on Sunday morning (AEST).

They took a while to find their groove and weren't at their best as they eased into their work but the two tennis heavyweights still managed to win the first set 6-4 in 45 minutes. Things only went up from there.

Williams and Murray were a more intimidating proposition in the second set as they showed their German and Chilean opponents no mercy, dropping just one game and closing out the second set in 31 minutes to complete the 6-4 6-1 victory.

"I think it worked out well," Serena said, before answering diplomatically about who the boss on court was. "We're a team. There's no 'I' in team."

Murray added: "We were just saying before the match that we're both the younger sibling so we're both used to being bossed around by our older brother and sister."

Both stars said they had lots of fun playing together and had only complimentary things to say about each other.

"For me, it's definitely awesome to share a court with Andy, especially this particular stage. Like I said, whenever you're a grand slam winner, you always learn something," Williams said.

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"But, yeah, still young in our relationship on the court. We still have a lot to learn."

Murray added: "For me it was a great experience being back on Centre Court with Serena after the last year or so being tough. It was nice. I enjoyed it.

"The thing that's impressive as well, is after the amount of success that someone like Serena has had for such a long period, to still be out there, whatever, 8 o'clock at night, having already won a singles, and just wanting to win and being competitive. That's impressive.

"I don't think people always appreciate how difficult that is to do I think because of what, like, Serena and Roger (Federer) have done for such a long period. It's kind of taken for granted a little bit. But it's impressive."

Before their opening hit-out together, Williams said she gets along great with Murray and is hoping the pair can go deep into the mixed doubles draw, which she believes will help her in singles.

"I always ask about his girls. I think his youngest daughter is almost the same age as my daughter, just a month apart. That's pretty cool," Williams said.

"I feel like I always play doubles, and the doubles really is able to help my singles game. That's super, super important for me.

"Andy and I both love the competition. I know we both want to do well. We're not here just for show. We want to play well. We both have been champions at Wimbledon. It's like we want to continue to do that.

"We don't feel pressure. Like I said, we really want to win. We'll see what happens. We know what it's like to win. We also know what it's like not to win. Obviously we want to do our best to get there."

But Murray knew going into the competition he needed to follow one unavoidable demand.

"I always play the forehand side. If you want to play with me, I play forehand. It's just the only rule I have," Williams said.