Roger Clemens' lips were pressed together tight, the corners turned slightly upward, his mouth pulled wide.

"There's only one interpretation," said Dan Hill, an expert in analyzing facial expressions, "and that's fear."

Hill doesn't profess to be able to declare with certainty whether the star pitcher or his former trainer, Brian McNamee, was telling the truth during their testimony before Congress today. But after viewing video clips of portions of the hearings, Hill concluded Clemens seemed more nervous than McNamee.

"To be fair, it could be fear of being unfairly stripped of the Hall of Fame," Hill said in a phone interview. "He also could be lying."

Hill is the president of Sensory Logic, a Minnesota-based marketing research company that analyzes consumers' facial expressions. He said Clemens showed signs of anger and disgust, pushing his lower lip and chin upward and pressing his lips together.

"It's the same body language as when he prepares to overwhelm a batter," Hill said. "He's a bulldog trying to will himself through the testimony."

But Clemens also repeatedly licked his lips and looked down.

"That's all signs of avoidance, possibly shame, absolutely nervousness," Hill said.

He thought Clemens seemed particularly anxious, gulping and licking his lips, when questioned about the testimony of former teammate Andy Pettitte's wife. In her affidavit, she said her husband told her about a conversation he had with Clemens in 1999 or 2000 during which the seven-time Cy Young winner admitted using human growth hormone.

McNamee may have looked "beaten down" as he was drilled by members of Congress, Hill said, but he appeared more confident than Clemens.

"He does not look like he's broken or wavering or nervous," Hill said.