It was "one of the few things that he lacked" in his already strong palmarès.
The 31-year-old Manxman has won the world championship road race, Milan-San Remo, the Tour's green jersey, and now, has worn the leader's jersey in all three grand tours including the big one in France.
"This was one of the few things that he lacked. It narrows it down to only a few objectives or goals that he has left to achieve," Dimension Data Performance Manager Rolf Aldag told Cycling Weekly.
"If there are one or two goals still out there that he can add to his palmarès, he can look back and say he achieved it all when he ends his career. The Olympic gold medal is clearly still out there for him, it would've been nice for him to win it in 2008. On the road? It's just for him to repeat success, to be twice world champion would be nice in Qatar later this year."
Cavendish joined South African team Dimension Data this winter after three years with Etixx-Quick Step, one with Team Sky and the first five years with T-Mobile/Highroad.
"He's won 27 stages, but the yellow jersey for him is amazing," Etixx-Quick Step General Manager Patrick Lefevere said.
"I would've loved to see Marcel Kittel in the yellow jersey for our team, but if someone else could win then it's Mark because we spent three years together and had a nice time.
"A wounded animal is always the most dangerous. You'll never forget somebody who's dangerous like him. I had the impression that everyone was always speaking about Greipel and Kittel, and no one, at least in Belgium, was speaking about Mark.
"It's a bonus in his career to have that yellow jersey, if he stops his career now he can say I wore the Tour's jersey."
Watch: Highlights from stage one of the 2016 Tour de France
Cavendish wore the jersey for the start of stage two in Saint-Lô. Tour Director Christian Prudhomme smiled despite the rain and said, "Cavendish winning yesterday to take the yellow jersey was a perfect beginning for the Tour de France."
Cavendish moved closer to overtaking Bernard Hinault and becoming the Tour's second most successful stage winner. The Frenchman counts 28 wins and Eddy Merckx holds the record with 34.
"I've been a part of a lot of stage wins with him so it's nice to finally get the yellow jersey," long-time lead-out man, Mark Renshaw said.
"For sure we don't win as many races as we used to do back a few years ago, but he's still the same rider and he's still got a lot of potential so hopefully we can get another stage win and increase the number of wins he has.
"If you take away the time trial wins that Eddy Merckx had he's still the most winning rider so yeah he's proven that he's one of the best ever."
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