LONDON -- Tony Romo has had two back surgeries in the past year, and he missed a game last week with two small fractures in his back.

But Cowboys owner Jerry Jones said he's more concerned with Romo's age -- 34 -- than his back, which is among the reasons he doesn't expect Romo to retire anytime soon.

Besides, Romo is in the first year of a six-year, $108 million contract extension.

"I think it's realistic for him to play five more years," Jones said. "I'm aware of his back. Only God knows what is in store for his back. I've seen backs out there that you wouldn't believe how they look on the MRIs and how they look on X-rays.

"If you're concerned about his future, then look at his age, and you might say, boy, you need to be thinking about a time when he doesn't play. I don't look at it much differently than that with his back, because there have been three very different types of injuries that have caused him to miss games with his back."

That's true, but it's hard to believe there's not a cumulative effect regarding Romo's back. Then again, Jones will tell you he's an optimist by nature.

It's the way he views the world, and the way he's looked at his football team for years. What it means, though, is the Cowboys probably aren't going to spend a high draft pick on a quarterback anytime soon.

Jerry Jones thinks Tony Romo will play at least five more years. Joe Robbins/Getty Images

Romo returned to practice Thursday, and Jones expects him to play Sunday against Jacksonville.

If Romo's healthy -- and that's a big if -- he's still among the best quarterbacks in the NFL. He has 15 touchdown passes and six interceptions and a passer rating of 103.6 this season. In the last two seasons, he has 41 touchdown passes, 15 interceptions and a 14-9 record in his 23 starts.

"Obviously he's playing a very physical game. I feel that as he moves along in his career, he will make any adjustments he has to make to help protect himself," Jones said. "If he needs to get it out quicker, if he needs to do some things that he might have done years ago, I think he'll adjust to that. The good ones have done that as they've moved along in their career.

"I'm planning on him having at least five years of playing at a level that would allow us to be possible contenders from that position, and maybe not doing some things that he had earlier as well or maybe with the energy or the efficiency he has, but maybe doing other things better. That's [what] happens in the NFL with players who play that position."