Denver Broncos receiver Wes Welker is expected to be held out of the team's final two regular-season games as he recovers from two concussions in a span of three weeks. Welker resumed light physical activity Thursday. On Friday, he will be formally ruled out of the Broncos' game Sunday against the Houston Texans, according to a team source. League and team sources also say Welker will be held out of Denver's regular-season finale Dec. 29 against the Oakland Raiders. The team's hope is that Welker, who left games in Week 11 and Week 14 with concussions, will recover in time to play in the postseason. Welker continues to be evaluated by the team's medical staff and an independent doctor as part of the league's concussion protocol. A third concussion in such a short span could end Welker's season, and one source said the player's well-being is "still the highest priority." Welker has not been medically cleared to practice, but on Thursday he spent some time working with the strength and conditioning staff in the team's weight room. Coach John Fox said Welker also did limited on-field work outside. "The exercise is picking up,'' Fox said after practice. "They're doing more and more with him in the weight room, running around out here a little bit and ... he's doing better every day.'' Welker has not practiced since leaving the Broncos' Dec. 8 victory over the Tennessee Titans shortly before halftime. He was taken from the field after being hit by safety George Wilson, having suffered a concussion as well as a neck injury on the play. Welker suffered a concussion on Nov. 17 as well, during the team's 27-17 victory over the Kansas City Chiefs.