The Dallas Cowboys (2-1) look to continue their surprising start to the season despite several injuries to key players while the San Francisco 49ers (1-2) look to snap a two-game slide and seek some defensive presence when the rivals clash in Week 4 Sunday afternoon at Levi’s Stadium in Santa Clara, California.

While the Cowboys have looked sharp behind rookie quarterback Dak Prescott and are coming off an excellent 31-24 victory performance over Chicago, head coach Jason Garrett could be without another top star after losing starting quarterback Tony Romo before the season.

The Cowboys are learned Wednesday that Pro Bowl wide receiver Dez Bryant suffered a hairline fracture against the Bears. The team was waiting on results of an MRI and he was held out of practice on Wednesday.

The possible loss of Bryant could make things a lot more difficult for Prescott, who shown poise in the pocket in three starts. The 23-year-old has connected on 66.7 percent of his passes for 767 yards and one touchdown, while rushing for another 54 yards and two scores. But with defenses so worried over Bryant’s big-play ability, Prescott has targeted slot receiver Cole Beasley, who’s caught 20 passes for 213 yards off 25 targets.

To make matters worse, injuries to the offensive line are starting to pile up. Dallas is sixth in the league with 134 rushing yards a game, with rookie running back Ezekiel Elliott contributing 91.3 yards per contest.

But starting tackle Tyron Smith, who missed the Chicago game with a back injury, was held out of practice again on Wednesday and the Cowboys are now using a "wait and see" approach with left guard La’el Collins and his injured right big toe. It was originally reported earlier this week that Collins was heading to the injured reserve list due to the ligament injury and subsequent surgery, but Cowboys owner and general manager Jerry Jones said an operation may be less likely, and ESPN reported Collins is seeking a second opinion.

“He seems to be getting better. He seemed to be moving around more comfortably,” Garrett said of Smith, accord to the team’s official site. “We continue to get feedback from the player, see how he feels. But he moved around better today than he did yesterday, and we’ll just see how he functions as the week goes on.”

Meanwhile, the 49ers and first-year head coach Chip Kelly are trying to regain some sort of defensive ground after suffering two consecutive losses by 19 or more points and surrendering 947 total yards.

San Francisco was outscored 24-3 in the first half against NFC West rival Seattle last week and eventually succumbed to a difficult 37-18 loss spurred on by a 4-for-15 conversion rate on third down. The 49ers are currently 24th in the NFL on third down, with a success rate of 34.8.

But under Kelly’s offensive scheme, the 49ers are running the ball quite well. They gained 135 total rushing yards against Seattle’s usually stout unit, 102 of which came from running back Carlos Hyde, who also scored both of San Francisco’s touchdowns.

Kelly will need more from quarterback Blaine Gabbert, whose 68.6 passer rating is better than only two others in the NFL while his 55.2 completion percentage is the second-worst in the league.

Game Time: Sunday, 4:25 p.m. ET

Betting Odds: Dallas -3

Over/Under: 46 points

Prediction: Dallas over San Francisco, 17-10