CHICAGO – The Sharks beat the Blackhawks on Tuesday night at United Center, but there was concern for defensemen Brenden Dillon, who left early in the first period and did not return.

After the game, head coach Pete DeBoer called it an “upper body [injury], [and] we’ll see how he is tomorrow.”

Dillon’s last shift came a little more than five minutes into the opening period of the Sharks’ 2-0 win. He was credited with a hit on the Blackhawks’ Jiri Sekac, and was seen favoring his shoulder area shortly after.

[INSTANT REPLAY: Sharks pull off upset, shut out Blackhawks]

The Sharks have struggled when down one of their regular defensemen. When either Justin Braun, Marc-Edouard Vlasic or Paul Martin is out of the lineup, the club is 1-6-1 with a goals-against average of 4.00.

Dillon, who has six points (1g, 5a) and a plus-7 rating, has played every game this season, as has Brent Burns.

The Sharks have been able to dress the same six defensemen for each of the past 25 games. Seventh defenseman Matt Tennyson has not played since Dec. 8, although he did dress on Dec. 20 against the Blackhawks without taking a single shift.