The moment her defenses start to crumble, her concentration falters.

This concentration never faltered through the stated program and the four encores I stayed for afterward.

Angela's trained eye began to scan the slide in an orderly fashion, but her concentration faltered.

His concentration faltered, and he shot a glance to the ground.

His concentration falters, however, and time resumes, permitting Sylar to stop the sword's movement.

"If your concentration falters at all, you pay the price."

Unfortunately, she was a good enough horsewoman, her concentration never faltered.

The sensation of falling was overwhelming, and my concentration faltered, making it worse.

If its concentration faltered at times in the Beethoven, it handled much of the difficult counterpoint cleanly.

His concentration might falter at just the moment that one of the sentry-minds happened to be listening to the area he was in.