WATCH: Controversial scenes as Stefanos Tsitsipas receives coaching warning after father Apostolos breaks new rules at US Open

Stefanos Tsitsipas was handed a coaching violation at the 2025 US Open after his father, Apostolos, breached the newly implemented rules. It marked one of the first recorded infractions since the regulations came into effect earlier this year.

On Thursday, August 28, 26th seed Tsitsipas took on Daniel Altmaier in the second round of the 2025 US Open. The competitors fought toe-to-toe before the German won the deciding point in the first set tiebreak.

Tsitsipas, who has been undergoing a tumultuous season, including his on-court performances and coaching changes, made a remarkable comeback to win two sets and lead 2-1.

In the fourth set, with Altmaier up a break and leading 5-3, Apostolos Tsitsipas, father and coach of the Greek star, appeared to give verbal instructions from the opposite end of the court.

Gill Gross 🌆

@Gill_Gross

Apostolos Tsitsipas just got a warning for coaching. Maybe the first one I’ve seen since coaching was largely legalized. The offense was delivering verbal instructions to Stefanos when he was on the opposite side of the court. That’s still not allowed.

Under the updated coaching rules, verbal guidance is only permitted when on the same end, a change from the previous total ban. Apostolos, who has a history of such infractions, became one of the first to be penalized under the new system.

Watch the video below:

The instructions, however, did not seem to have worked as Tsitsipas lost that game and the set. The match went into a deciding fifth set.

---

Stefanos Tsitsipas' poor run continues as he faces a shock upset against Daniel Altmaier at US Open

Stefanos Tsitsipas at the 2025 US Open - Source: Getty

In the deciding fifth set, Daniel Altmaier earned a key break and clinched a solid five-set win over Stefanos Tsitsipas, with the score reading 7-6(5), 6-1, 6-4, 3-6, 7-5. Post-match, tensions escalated at the net.

Tsitsipas complained about Altmaier’s underarm serve and appeared to own up to intentionally aiming a shot at his body in the fourth set, despite apologizing for it earlier. Altmaier, however, wasn’t having it. He cut short any conversation, walking away quickly to celebrate.

Tsitsipas’ struggles extend beyond this loss. In 2025, he failed to reach the third round of any Grand Slam. Recently, he even faced a shocking first-round exit at Wimbledon.

His ranking has dropped sharply, falling out of the top 20 for the first time since 2018. He underwent coaching changes, including a brief stint with Goran Ivanisevic, then reunited with his father, Apostolos, hoping to regain form. However, the results haven’t followed.

Meanwhile, Altmaier has reached his first US Open third round. The German will take on eighth seed Alex de Minaur for a spot in the coveted second week of the Major.