Giants wide receiver Mario Manningham sustained a concussion in a 29-10 loss to the Tennessee Titans but did not alert the medical staff until Sunday night. Manningham did not practice Wednesday, and his status for Sunday night's game against the Bears is uncertain. He was unavailable for comment on Wednesday. Manningham had medical tests Monday, and coach Tom Coughlin said he appeared to be fine. On Wednesday, Manningham performed balance and coordination tests, according to a team spokesman, but did not undergo the ImPACT test, a computerized evaluation of memory, brain processing and visual motor skills. 'He'll be tested again, and we'll see how that comes out,' Coughlin said Wednesday. 'We're a little bit surprised that there's an issue.' Coughlin did not know the severity of the concussion or when Manningham sustained it during the game. It was also unknown whether Manningham felt the effects of the concussion during the game or if the symptoms developed later. Manningham had six catches for 78 yards, which does not include a 43-yard reception in the third quarter that was nullified because of a penalty. For the season Manningham leads the Giants with 238 yards receiving. In Manningham's place, the Giants temporarily made the rookie Victor Cruz their third receiver in practice. Cruz, an undrafted free agent out of the University of Massachusetts, won over the front office and fans alike with a strong preseason, highlighted by a three-touchdown performance against the Jets on Aug. 16. JET HAS SUCCESSFUL SURGERY Jets nose tackle Kris Jenkins had surgery on his left knee Wednesday. The doctors, Ken Montgomery and Elliott Hershman, told Jenkins' wife that they repaired his anterior cruciate ligament, which he also tore last year. They also did some work on the meniscus but found less damage there, as it had already started to heal. They also discovered a bone bruise. --GREG BISHOP 