Stefanos Tsitsipas' clash at the net with Daniel Altmaier after losing at the 2025 US Open was not well-received by fans. Many fans called the Greek a "sore loser" for his actions.The US Open has witnessed multiple controversies in its early days, and its latest one was provided by Tsitsipas. After losing the second-round clash against the experienced German player, the World No. 28 clashed with him at the net during their handshakes.Seemingly, Tsitsipas was upset about Altmaier serving underarm in the fourth set. The Greek even seemed to confirm that he had hit Altmaier intentionally during the match, despite apologizing to his opponent at that moment.During the altercation, Tsitsipas was trying to create a scene before Altmaier decided that was not how he wanted to celebrate his victory. He moved away from the conversation and went to applaud the crowd for their support in his triumph.Fans on X reacted to the incident and did not approve of the Greek's behavior."Tsitsipas is a big sore loser. Such shameful, petty and pathetic behaviour from him. He should be ashamed. Underarm serve is an absolutely valid tactic and it was like used 2 hours ago lol. Instead of being a sore loser, he should look into improving his game. Embarrassing clown," one fan wrote.SRF @S_RF_CALINK@Olly_Tennis_ Tsitsipas is a big sore loser. Such shameful, petty and pathetic behaviour from him. He should be ashamed. Underarm serve is an absolutely valid tactic and it was like used 2 hours ago lol. Instead of being a sore loser, he should look into improving his game. Embarrassing clown"Stefanos Tsitsipas will always be a sore loser,"another fan wrote."Did I hear that right? “Next time don’t wonder why I hit you.” If Tsitsipas meant underarm serves justify drilling opponents… that’s bottom-tier sportsmanship," a third fan commented.Here are some more fan reactions slamming Stefanos Tsitsipas for his behavior."Stef trying to take away from his moment, brutal loser," one fan wrote."Such a fraud lmao. Just realise you’re shit at tennis," another fan wrote.One fan referenced the earlier US Open controversy between Jelena Ostapenko and Taylor Townsend, where the Latvian was upset with her opponent for not apologizing after winning a let cord point. They wrote:"Why does everyone on Tour want their opponent to be nice to them during play all of a sudden? Players are there to win not make friends."Stefanos Tsitsipas manages a 2-4 record at Grand Slam events in 2025 after US Open exitStefanos Tsitsipas at the 2025 US Open - Source: GettyStefanos Tsitsipas' poor 2025 seems to have no end as he registered yet another early loss. The 2025 US Open looked like a chance for the Greek star to push for a solid end to his rather disappointing year. However, he could not take it.At the first Slam of 2025, the Australian Open, Tsitsipas was ousted in the first round by Alex Michelsen. His rankings were falling and form was dwindling before a ray of hope came in Dubai when he won an ATP 500 title. He notched some wins in the next few tournaments before falling in the second round of the French Open.Further misery ensued as he lost in the first round at Wimbledon. Amid this poor run, he had appointed Goran Ivanisevic, who replaced his father Apostolos, as coach. That short stint also ended in controversy, and Stefanos reunited with his father before the US Open.Apostolos, who has a history of being penalized for coaching, got a warning again during the US Open second round. Eventually, Stefanos lost the match and now holds a disappointing 21-17 record for 2025. He is ranked outside the Top 20 and might fall further.