WASHINGTON — Federal agent Jeff Novitzky returns for a third day of testimony today in the Roger Clemens perjury trial, while behind the scenes Clemens’ lawyers sought to strike the testimony of former teammate Andy Pettitte.

Last week, Pettitte testified that Clemens told him he had tried human growth hormone, only to say under cross-examination that he might have misunderstood Clemens. As expected, Clemens’ lawyers filed a motion asking that the jury not be allowed to consider the conversation between the two pitchers.

Pettitte said that it was “fair” to say that there was a 50 percent chance he misunderstood Clemens, his friend and one-time mentor.

“The court should not allow the jury to consider an alleged ‘admission’ that has all the weight of a coin flip,” Clemens’ lawyers wrote in a filing this morning, before the resumption of the trial.

Clemens is accused of lying to Congress in 2008 when he denied using HGH and steroids.