Sources – Christian McCaffrey will not return in Week 6, but there are reasons for encouragement

Christian McCaffrey will not be activated for Thursday night's game in Seattle against the Seahawks, league sources told ESPN on Saturday, although the 49ers' star running back is eligible to return.

The bigger question remains when McCaffrey, who has been on injured reserve since Week 2 with calf and Achilles tendonitis, can return.

McCaffrey's return depends on how he performs in practice, but for now there is some slight encouragement as the three-time Pro Bowler's calf and Achilles tendon issues have not returned following on-field work this week – his first on-field work since then have surfaced will be placed on IR, according to league sources.

Although McCaffrey is dealing with bilateral Achilles tendonitis, his problem is concentrated in one of his legs – and the other is doing better, according to sources. Sources say the bilateral Achilles tendonitis is not a concern. Sources told ESPN that McCaffrey is focused on avoiding setbacks as he continues to gain momentum in his return to play.

If his progress continues without setbacks, McCaffrey could return for a Super Bowl rematch against the Chiefs on Oct. 20, according to league sources.

According to sources, there is also a chance McCaffrey could return for a game against the Cowboys on October 27th. But more sensibly, the 49ers could opt to use McCaffrey for both games and then give him a week off to further prepare for their next game at Tampa Bay on November 10th.

The Niners don't know which of these weeks is the most realistic return date, but they do know that McCaffrey hasn't suffered any setbacks recently.

McCaffrey traveled to Germany last month to consult with a specialist in hopes of resolving the issue that had been bothering him since the start of training camp. The two-time All-Pro missed four weeks of practice before returning to the field on a limited basis before the season opener on Sept. 9 against the Jets. He was late for that game and then went on IR on September 14, two days after feeling soreness in his Achilles tendon after a practice.

McCaffrey, 28, led the NFL with 2,023 yards from scrimmage last season and tied for the league lead with 21 touchdowns and was named the AP Offensive Player of the Year.

Information from The Associated Press was used in this report.