All is not well with the Swiss Davis Cup Tennis Team. Over the weekend, Swiss teammates Roger Federer and Stan Wawrinka met in the semifinals of the ATP World Tour Finals in London. The two players were tied at five games each in the deciding third set of the match, and Wawrinka pulled away from a critical Federer serve at the last moment.

Federer, Djokovic to Meet in Final

Video footage of the incident is available, and just before Wawrinka becomes agitated, a woman's voice can be heard, and it sounds like she calls Wawrinka a cry-baby. He points towards the stands and starts admonishing the heckler, believed to be Roger Federer's wife Mirka, according to the Daily Mail.

Wawrinka may have already been frustrated with himself for letting three match points slip away earlier in the set, and the jeers from the stands, which appeared to be coming from court level near the supporters' bench, could have been the final straw. Wawrinka was livid that the heckling took place just prior to receiving a serve, and eventually the chair umpire had to step in to settle him down.

Wawrinka's Win Keeps Federer's Hopes Alive

Following the match, Federer and Wawrinka reportedly got into a heated exchange for nearly 10 minutes in a private room that the players were using as a gym. On Monday, the two men posted photos to Twitter claiming to be excited about the upcoming Davis Cup match, in which Federer and Wawrinka will be teammates.

However, Federer took his private jet to the match, whereas Wawrinka took the Eurostar, so perhaps some resentment still lies beneath the surface.