WATCH: Zverev Prematurely Celebrates Winning Set After Not Hearing Out Call

The opening set of Alexander Zverev's match against Adam Walton at the 2025 Canadian Open was an intense battle and included an unusual mix-up on the final point.

Zverev, playing his first match since losing in the first round of the 2025 Wimbledon Championships, was thoroughly tested by Walton. The Australian's consistency and intelligent shot selection caused issues for the ATP world No. 3.

This year's Australian Open runner-up managed to stay competitive and fight his way to a tiebreak. After more lengthy and grueling rallies, Zverev had a set point at 7-6 on his own serve.

The video below shows what happened next. Zverev hits his first serve down the line, but it lands narrowly long. The out call from the automatic line-calling system can be heard in the clip.

But Zverev thought the serve was in. He did not notice the system informing him, Walton, and those watching that the ball was out, and drained it out by screaming in delight after thinking he had won the set.

Umpire Richard Haigh swiftly interrupted by shouting "fault." When Zverev looked at him in surprise, the umpire called fault again to reiterate that the German had not completed the set and needed to hit a second serve.

Many in the crowd erupted with laughter at the unexpected moment. Haigh gave Zverev a brief smile before the three-time Grand Slam runner-up turned around to refocus after prematurely celebrating.

When Zverev returned to the line to hit a second serve, he had a slight smile on his face. That approach, rather than showing any frustration and becoming rattled, was probably the right way of handling it.

The two-time ATP Finals champion's response was emphatic. He hit an excellent deep second serve to the forehand of Walton, who could only produce a short reply. Zverev then struck a cross-court backhand into the corner.

Walton did well to even get that back into play, but Zverev was not to be denied. The 28-year-old completed the set with a forehand winner and could freely celebrate without any intervention from the line-calling system.

After screaming when he thought he had won the set on first serve, Zverev's reaction to actually taking the opener was more muted, briefly giving a fist-pump to those supporting him in Toronto.

Zverev went on to secure a 7-6, 6-4 triumph. The No. 1 seed will face Matteo Arnaldi on Thursday in the round of 32 in a contest that promises to be filled with more lengthy rallies and terrific shot-making.

Jannik Sinner and Carlos Alcaraz's withdrawals from the Canadian Open made Zverev the No. 1 seed. Although this gives him a better chance of winning the tournament, he must manage heightened expectations and pressure.

Novak Djokovic, Matteo Berrettini, and Grigor Dimitrov were among the other players who removed themselves from the entry list. Sadly, Dimitrov will also miss the 2025 US Open because of the injury he sustained at Wimbledon.

Zverev entered the Canadian Open after working with Toni Nadal at the Rafa Nadal Academy and hopes to collaborate with him more in the future, although the Spaniard's position at his nephew's academy complicates this.