OXNARD, Calif. -- Dallas Cowboys tight end Jason Witten will miss the rest of the preseason with a lacerated spleen and could be sidelined for the Sept. 5 season opener at the New York Giants.
Witten suffered the injury on the second series of Monday's 3-0 preseason opening victory against the Oakland Raiders.
The spleen was not ruptured and does not require surgery at this time.
The plan right now is for him to remain idle for the next 10 days and then re-evaluate the situation.
"It's a very serious injury, and we're really taking this thing day by day," Cowboys coach Jason Garret said. "He has to be very still and idle for the next week to 10 days, so you won't see him out here on the practice field; he won't play in the game this week or next week. We've just got to make sure he heals as well as possible, as quickly as possible.
"As you can imagine, spleens are internal organs, and there're serious injuries involved with those things. Asking Wit to be still and idle is a hard thing; that's the biggest challenge right now."
Witten, who has played with a fractured jaw and famously ran without his helmet, proved how tough it was too keep him idle when he gingerly walked onto the practice field during the team's morning walk-through on Wednesday. He watched for a few minutes before leaving. Asked how he was doing, Witten said, "I'll be all right" as he rode off in a golf cart after practice.
The Cowboys have 11 days between the opener and their Week 2 matchup against the Seattle Seahawks on Sept. 16.
"That is way premature, but it would give him two more weeks," Garrett said. "What factors most is his health. We are not going to rush anybody back before they are ready to go. It's a medical decision first and foremost."
Owner Jerry Jones, who said he held his breath when Witten took the blindside hit in the game, is focused on getting him healthy, not how long he will be out.
"I haven't thought about it at all," Jones said. "We're basically more interested in him resting this week and getting that thing healed. I really don't have any timeline."
Jones wasn't bothered by Witten playing three series in the preseason opener behind a patchwork offensive line.
"That's second guessing," Jones said. "He certainly went one play too long, from that standpoint. But I don't at all second guess that."
The injury is potentially a huge setback considering that Witten has led the team in receiving in each of the past five seasons and is quarterback Tony Romo's most reliable and trusted pass catcher.
He is just 55 catches from passing Hall of Famer Michael Irvin as the team's all-time leading receiver.
"It's big," Pro Bowl linebacker DeMarcus Ware said. "He was a big leader on offense. I don't even know long he is going to be out. We are going to miss him."
The Cowboys have little experience and little depth at tight end behind Witten after Martellus Bennett bolted to the New York Giants as a free agent in the off-season.
John Phillips, who returned to practice Wednesday for the first time since suffering an ankle injury last week that kept him out of the preseason opener, likely will start in Witten's place until he returns. The other tight ends on the roster are rookie sixth-round pick James Hanna and undrafted rookie free agent Andrew Szczerba.
The Cowboys moved quickly to bolster the tight end position for practice, signing Harry Flaherty and waiving injured guard Bill Nagy.
Flaherty is the nephew of head coach Jason Garrett and tight ends coach John Garrett.
Although Flaherty will be eligible to play, he might not be able to help much in Saturday's preseason game against the Chargers as he will not be allowed to practice in pads in Wednesday and Thursday's practice, adhering to the NFL's three-day waiting period.
The Cowboys will conduct a walk-through on Friday.
Clarence E. Hill Jr.