Andy Murray has defended using an underam serve in his four-set Wimbledon victory over James Duckworth and believes the tactic should be seen as smart.
The two-time Wimbledon champion recovered from a set down to win 4-6 6-3 6-2 6-4 against the Australian on Monday.
Murray maintained his record of having never lost in the first round at SW19, throwing in an underarm serve to help him win a point in the third set.
The Scot insisted using the underam serve, a move often associated with Duckworth's compatriot Nick Kyrgios, is a legitimate tactic and not a sign of disrespect to an opponent.
"He changed his return position, that's why I did it," Murray explained after the match.
"He was struggling a little bit on the first-serve return, so he stepped probably two metres further back. As soon as I saw him step further back, I threw the underarm serve in.
"I personally have no issue with players using it. I never have. Certainly more and more players have started returning from further behind the baseline now to give themselves an advantage to return.
"No one says it's disrespectful for someone to return from five or six metres behind the baseline to try to get an advantage.
"So I used it, not to be disrespectful to him, but to say, 'if you're going to step further back to return the serve to give yourself more time, then I'm going to exploit that'.
"I've never understood that [argument it is disrespectful]. It's a legitimate way of serving.
"I would never use an underarm serve if someone was standing on the baseline because I think it's a stupid idea because they're going to track it down and it's easy to get.
"If they stand four or five metres behind the baseline, then why would you not do that to try to bring them forward if they're not comfortable returning there? Tactically, it's a smart play."
Murray will face big-serving American John Isner in the second round on Wednesday, having won each of the duo's eight previous head-to-head meetings.
He was happy with how he felt physically after beating Duckworth, having returned from the abdominal injury he suffered while reaching the Stuttgart Open final earlier this month.
"The last few days when I've been serving was fine," he said. "I went to get an ultrasound scan on it on Saturday after my practice just to see how it was progressing.
"It was all clear for the first time on the scans, which is really positive. I wanted that kind of for my own peace of mind to know that the injury has healed.
"Obviously I still need to take precautions and still do some rehab and protect it when I can, but in the match it was absolutely fine."