Cavaliers rookie Kyrie Irving has his first NBA injury — a concussion.

The star guard, who has lived up to being the No. 1 pick in this year's draft, was kept out of Wednesday night's game against the Los Angeles Clippers with a head injury. The team did not disclose Irving's concussion until moments before tip-off. There is no immediate timetable for his return.

The Cavaliers said in a release that Irving was kneed in the head during the fourth quarter of Tuesday's game at Miami. He complained of a headache after the game and that it worsened overnight and while he warmed up on the floor Wednesday.

Irving was evaluated by Cleveland's medical staff, and team physician A.J. Cianflocco diagnosed the 19-year-old with a concussion shortly before the game.

Coach Byron Scott did not mention Irving's injury or the fact that he was struck in the head during his pregame media briefing.

Ramon Sessions started at point guard in place of Irving, who had started each of Cleveland's first 23 games.

Irving is averaging 18 points and 5.1 assists and has made several clutch fourth-quarter plays for the Cavs. He was selected to participate in the "Rising Stars" game during All-Star weekend next month in Orlando.

Scott said that while Irving has had a strong start to his pro career, there are too many quality point guards in the Eastern Conference to warrant him making the All-Star team. Reserves for the squad will be announced on Thursday.

"He's definitely raising some eyebrows," Scott said.

Irving's injury prevented him from matching up with Clippers guard Chris Paul, who believes the Cavs have a budding star.

"He's really good with the ball and his decision-making and stuff like that. He can really play," Paul said.

Paul played for Scott in New Orleans and said Irving is fortunate that he's being groomed by the coach.

"There couldn't be a better situation for him than starting off his NBA career playing for Coach Scott," Paul said following the Clippers' morning shootaround. "He is really going to let him go and give him an opportunity to learn on the go. Coach Scott led me to Rookie of the Year and it looks like he's about to do it again."