Grove, the second-year player out of Virginia Tech, was injured during a play-fake pass from quarterback Kerry Collins to Randy Moss in the third quarter of Sunday's 19-13 win over Dallas, Oakland's first win of the season.
Grove had to be helped to his feet and was taken to the locker room and did not return. Afterward, both Grove and head coach Norv Turner sounded optimistic when talking about the injury. But on Monday, reality brought the bad news.
''Jake had his knee scoped this morning,'' Turner said. ''It was a very short procedure. He has a slight torn cartilege and it was scoped. It's probably in that 3-4 week range.''
That means that Grove, who started eight games at right guard as a rookie before moving back to center this year, might not return until after the team's Oct. 30 game in Tennesee.
That also means that Treu, who doubles as Oakland's long-snapper, will once again step into the spotlight. He played nearly the final 25 minutes of the game against Dallas after Grove was hurt and was key in helping spring running back LaMont Jordan free for a season- and career-high 126 yards.
It's a familiar role for Treu.
In 2001, he filled in as the starter for 14 games when Barret Robbins suffered a season-
ending knee injury. In 2002 when Robbins went AWOL on the eve of Super Bowl XXXVII, Treu again stepped in. Same story in '03 when Matt Stinchcomb failed as the starter and Robbins was injured and missed the final four games of the regular season.
In 2004 Treu started all 16 games but not before holding off Grove in training camp. Even then, it was a temporary situation. Grove was dubbed the starter during the team's offseason mini-camp and nothing changed once the season began.
''When we moved back Jake back in there and had the conversations with Adam about it, he handled this thing extremely well,'' Turner said. ''He knows in the National Football League that there are going to be opportunities when you are going to be asked to get back in there, into action. He handles it awfully well.''
Grove's injury was one of the few blights on the Raiders' first win of the season, one that ended a five-game losing streak dating back to 2004.
Oakland's defense continued its strong play, kicker Sebastian Janikowski awoke from his season-long slumber, Jordan and the running game got untracked, and Collins and Moss added yet another one for the highlight reel.
Making sure that good feeling carries over past the bye is critical. Oakland plays San Diego coming out of the break and can ill-afford to fall further back in the AFC West race.
How that plays out could depend on how well the offensive line does transitioning from Grove to Treu, the team's longest tenured player on the current roster, having joined the team as a third-round pick in 1997.
''I think there's obviously differences,'' Turner said Monday when discussing his two centers. ''Adam brings a lot more experience and I think some of the things that at times have gotten to us, some of the calls in terms of protection and all that, Adam's a lot more comfortable with.''