Marshon Lattimore's hamstring tightens up at NFL combine

Durability questions linger around Lattimore (0:50)

Todd McShay weighs in on DB Marshon Lattimore's reported hamstring injury that raises questions about his endurance. (0:50)

After saying he was "100 percent fine," Ohio State cornerback Marshon Lattimore suffered a hamstring injury Monday at the NFL combine, sources told ESPN's Adam Schefter.

Lattimore's hamstring "tightened up on him, it's nothing serious," the source said.

Lattimore denied he had a hamstring injury, tweeting Monday that he had a hip flexor issue.

"It was TOTALLY his ham. He pulled up at end of 40. I've never ever seen anyone pull up for a hip flexor. But I have for hammys many times," one source texted to Schefter.

Lattimore, one of the most highly rated cornerbacks on the draft board, is expected to be ready for his March 23 pro day.

Before his injury Monday, Lattimore ran a 4.36 in the 40-yard dash, and had a vertical jump of 38.5 inches and a broad jump of 11 feet.

A tight hamstring wouldn't be a big deal, except hamstring issues have dogged Lattimore for two seasons. He missed the entire 2014 season and more than half the 2015 season. He said he tore the left hamstring in 2014, and then injured his right hamstring in 2015.

Lattimore has said the first thing NFL teams ask him about is his hamstrings. "[I] tell them about my hamstring situation, but I'm 100 percent fine right now," he said. He also said he was sent for an additional MRI since arriving at the combine.

Lattimore said he added yoga to his preseason routine and thinks that helped him stay healthy in 2016.

"It's not luck at all. I did yoga, I did extra stretching exercises and all that,'' Lattimore said. "It's no luck. ... I knew [the injuries were] going to come up so I'm not annoyed, I'm just enjoying the process right now.''