Dallas Cowboys quarterback Dak Prescott insisted he will be fit to face the Philadelphia Eagles in a crucial NFL showdown as both teams vie for a playoff berth.Prescott’s availability for Sunday’s blockbuster has been questioned due to a right shoulder sprain suffered in the opening quarter of last week’s victory over the Los Angeles Rams. “It’s always fun just challenging yourself, and right now it’s just a mental challenge. Same preparation in the game plan, if not doubling down, since I don’t get those physical reps.”On Prescott’s limited preparation, Cowboys owner and general manager Jerry Jones told 105.3 The Fan: “You like for everybody to be out there practicing, but I’m totally convinced that he’ll be in top form.”And we’ve got to have him in top, and he will be in top, form. So, I think the situation has been described accurately. These are things that guys play with and they practice with. So, I think we’re in good shape. Not worried about it.” The NFC East title will be on the line when the Cowboys visit the Eagles at Lincoln Financial Field – both franchises sharing 7-7 records atop the division with two games remaining in the regular season.NFL WEEK 16: Clinching scenarios for Cowboys, other teamsPrescott allayed fears over his availability, telling reporters on Thursday: “I’ll be good to go Sunday.”I’m getting better, simple as that. Mobility, function of it, it’s all improving. That’s the key. That’s the goal . . . It’s just annoying. I mean, it’s nagging. Definitely dealt with a lot more pain, so it’s just annoying.”It [the injury] happened early in the game [against the Rams] and I was fine, played throughout the whole second half without it being a problem, without it being an issue. And I expect the same this Sunday.”Jerry Jones believes that Dak Prescott will be in “top form” for Sunday.Updates presented by @SleepNumber— Dallas Cowboys (@dallascowboys) December 19, 2019Prescott, who did not attempt a throw during Thursday’s portion of practice open to the media, added: “It’s frustrating. I’m a guy that likes to be in the action. I don’t like to sit back, don’t like to take any reps off, but it’s good mentally.