Ben Shelton has called on tennis bosses to impose a shot clock on second serves in the wake of his heartbreaking US Open final defeat by Alexander Zverev.Zverev overcame the American in four sets on Sunday, with the No 1 seed routinely bouncing the ball more than a dozen times before hitting his serve. As it stands, players have 25 seconds to start their first service motion after the end of the previous point. There is no strict time limit on second serves, with the rules stating only that it must be hit ‘without delay,’ and no maximum number of ball bounces.Zverev’s habit has sparked calls for change from tennis legends such as Andy Roddick and John McEnroe. And, in the wake of Sunday’s final, Shelton echoed those frustrations. ‘I definitely think for a first serve, you should be able to do whatever you want – you can use the full 25 seconds every time,’ the American said.‘I think that there should be some sort of rule… limiting time on second serve. You shouldn’t have unlimited time. For our sport, for the fans, I think it’s tough to be sitting there that long for the next play, the next action to happen.’ Ben Shelton called for a rule change after losing to Alexander Zverev in the US Open final The No 1 seed routinely bounces the ball more than a dozen times before hitting his serve Shelton was beaten in four sets by the No 1 seed in Sunday’s final in New YorkShelton added: ‘I’m sure at some point it will be something that these tournaments look at just because there is such a delay in play in some matches.’According to reports, Zverev had bounced the ball more than 12,000 times over his first five matches at this US Open. Following his semifinal loss to the German, Karen Khachanov claimed: ‘The way he bounces the ball, it annoys not only me, of course, [but] a lot of players.’Throughout Sunday’s final, Shelton would wait before setting himself for Zverev’s serve, only sinking into a crouch once his opponent had begun his exhaustive routine.That landed him in hot water with chair umpire Marijana Veljovic and afterwards Shelton took issue with another rule around the return of serve.‘She was telling me I need to get to the line earlier, and I was like: “He can start his routine whenever he wants,”’ Shelton explained.‘I promise you there will never be a time where he serves and I’m not ready… if he’s bouncing the ball 20 to 25 times, I shouldn’t have to just sit there for that… I think that is a stupid rule.’Shelton added: ‘He never does less than ten bounces… I’m not going to sit there in a ready position with my knees bent, tension in my body for 30 seconds while I’m waiting.’After his victory over Khachanov, Zverev claimed his exhaustive routine is not deliberate, insisting: ‘I’m not counting in my head… I’m not getting a certain number or anything like that. I don’t know why it increased so much.’