Some people seem to do fine without much some form of pre-activity warm-up or stretching of any kind but many would say this increases the likelihood for injury in a sport like tennis.
For me personally, I can't play tennis without going through a warm-up routine which includes doing (at home before I even go to the courts) no weight squats/lunges, light upper body weights, giving my calves the rolling-pin treatment and some mild stretches especially stuff like torso twists and for shoulder joint mobility.
It's nothing too hectic but when I get to the club 15 to 20 mins later and start hitting I really notice the difference. It makes for a much better start to the match as well and, anecdotally, seems to delay fatigue during the game to some extent as well.
Original Pro Staff 85, leaded to 370g, hybrid poly/syn gut set-up, 48-52-ish lbs.