ANAHEIM, Calif. -- The Texas Rangers might be without two key performers when they open an important series against the Los Angeles Angels on Monday.

Third baseman Joey Gallo and right-hander Matt Bush are both in the concussion protocol, and they did not travel to Anaheim with their teammates.

Gallo and Bush collided while chasing a popup in the eighth inning Sunday in Texas' 3-2 home loss to the Chicago White Sox. Gallo sustained a non-displaced nasal fracture and a swollen upper lip, while Bush bruised his right knee.

Both players are due to be re-evaluated Monday, and if cleared, they could head to California

Gallo has 35 homers, tied for second in the American League. The 23-year-old is batting .205 with 65 RBIs in 113 games this season.

Bush, 31, has a 3-4 record with 10 saves and a 3.04 ERA in 49 appearances.

The Angels and Rangers are two of eight teams bunched within five games of each other in the battle for the American League's second wild-card spot.

Los Angeles (64-60) is currently tied for the second spot with the Minnesota Twins (63-59), while Texas (61-62) is 2 1/2 games behind. A Rangers sweep would move them ahead of the Angels.

Regardless of the results of the upcoming series, there will be five weeks of baseball remaining, so Texas' Monday starter, Cole Hamels, said the mindset of his teammates needs to reflect that.

"It's not even September," Hamels said. "We have a team that is ahead of us. I think we all understand that the end goal is to try to get to that wild card. They're ahead of us. For us, we have to go out and play good baseball.

"Obviously, winning is more important because when you lose to a team that is ahead of you, (it) can put yourself in a bind. They've been playing good baseball, we've been playing good baseball. It's a matter of going out there and taking care of business."

Hamels (8-1, 3.48 ERA) owns an impressive career record against the Angels. Though he has been in the majors since 2006, most of that was with the Philadelphia Phillies in the National League. He has faced the Angels just seven times, going 3-1 with a 2.45 ERA and one complete game.

The left-hander has opposed the Angels twice this season, going 1-0 with an 0.61 ERA.

Big games are nothing unusual for Hamels, who has started 16 postseason games in his career, including three World Series games. He was the World Series MVP for Philadelphia in 2008.

"For us, it's just continue to play good baseball," he said. "The hitters have been putting up big innings. Our starters have to maintain the presence of pitching deep into ballgames. The bullpen is really starting to come around and lock in. You want to work well together at the right time, and obviously this is heading into the right time."

The Angels are coming off their best road trip of the season, winning seven of nine in Seattle, Washington and Baltimore.

Tyler Skaggs (1-3, 3.63 ERA) will start for Los Angeles on Monday, having given the club a boost with his return to the rotation after missing three months with a strained oblique.

In this three starts since returning Aug. 5, Skaggs is 0-2 with a 2.93 ERA, including 6 1/3 scoreless innings against the Mariners on Aug. 10.

Skaggs is 2-1 with a 5.46 ERA in six career starts against the Rangers, and that includes two starts in April this year before his injury. Skaggs got a no-decision in both games, giving up six runs in 10 innings, but the Angels ultimately won each time.

Skaggs will get the benefit of an Angels offense that has hit well of late. Los Angeles scored five or more runs in six of the nine games on the trip.

Shortstop Andrelton Simmons was not part of much of that success, going 0-for-19 during one stretch of that trip. Simmons snapped the streak with a double on Saturday, then hit a key home run Sunday in Los Angeles' 5-4 win at Baltimore.

"I didn't feel the best at the beginning of the week, but I felt better toward the end," Simmons told the Orange County Register. "It happens. I'm happy I got that feel back. Hopefully I can get back to what I've been doing the majority of the season."