When the moment comes, Serena Williams will use Roger Federer as a yardstick for calling time on her illustrious career.
The 36-year-old marked her first Wimbledon appearance since the 2016 final with a straight-sets victory over Arantxa Rus, Williams showing great power and desire to brush aside the Dutchwoman.
Williams' win came hours after defending champion Federer also breezed into round two, the Swiss hunting an unprecedented ninth crown.
His dominance is matched by Williams' in the women's game, the American having won seven of her 23 grand slams in SW19.
Federer hopes to extend his career long enough for his four-year-old sons to remember him in action, and Williams has no intention of stopping before him.
"I'm just playing until Roger stops," she joked during her post-match media conference.
"So... Gosh, how long? Did he put a time limit on it?
"[Has] he said how many more years he's going?"
Four years was the reply, to which Williams responded with: "Well, here I am. We in it. We in it together. As long as he's here, I'm going to try to be here."
Of her 7-5 6-3 win over Rus, Williams was delighted to have secured an early win and hopes her game will slowly return after struggling with a pectoral injury since Roland Garros.
"It felt good to play, just to be back on the grass," she said.
"I'm just taking it one [match] at a time. I don't think I was at my best today, but I'm practicing much better.
"I feel as long as I keep going, hopefully I'll be able to get there.
"My serve is a little playing catch-up, but it's doing better than I could have hoped, to be honest. It's all on the right track."
