Stefanos Tsitsipas, of Greece, plays Philipp Kohlschreiber, of Germany, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

Stefanos Tsitsipas, of Greece, reacts while playing Philipp Kohlschreiber, of Germany, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

Stefanos Tsitsipas, of Greece, reacts after defeating Philipp Kohlschreiber, of Germany, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

Stefanos Tsitsipas, of Greece, reacts after defeating Philipp Kohlschreiber, of Germany, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

Philipp Kohlschreiber, of Germany, reacts after wining a game while playing Stefanos Tsitsipas, of Greece, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

Philipp Kohlschreiber, of Germany, plays Stefanos Tsitsipas, of Greece, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

Stefanos Tsitsipas, of Greece, plays Philipp Kohlschreiber, of Germany, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

Stefanos Tsitsipas, of Greece, serves to Philipp Kohlschreiber, of Germany, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

Stefanos Tsitsipas, of Greece, plays Philipp Kohlschreiber, of Germany, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

Stefanos Tsitsipas, of Greece, plays Philipp Kohlschreiber, of Germany, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

Philipp Kohlschreiber, of Germany, bottom, plays Stefanos Tsitsipas, of Greece, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)

Philipp Kohlschreiber, of Germany, reacts while playing Stefanos Tsitsipas, of Greece, during the first round of the tennis competition at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Seth Wenig)