ENGLEWOOD, Colo. — Although the schedule gets easier for the Denver Broncos this month, the degree of difficulty in reaching the playoffs keeps going up.

The Broncos (6-6) lost leading wide receiver Emmanuel Sanders to a ruptured left Achilles tendon on Wednesday. He was hurt in a non-contact drill at the beginning of practice.

The 31-year-old receiver was placed on injured reserve and on Wednesday night he tweeted , "If you know me then you know nothing can keep me down. I've overcome too much in life to let this stop me. I'll be back next year w/ a bigger chip on my shoulder ... I PROMISE!"

The Broncos quickly claimed wide receiver Andre Holmes off waivers from Buffalo, giving them a seventh-year veteran to go with their four remaining receivers, all of whom made their NFL debuts this season.

Sanders, who led the team with 71 catches for 868 yards and four touchdowns in a bounce-back year, was injured on a routine route. He sensed the gravity of the injury as he crumbled to the ground, tearing off his helmet and rolling it away as teammates and trainers rushed toward him.

"It didn't look good," coach Vance Joseph said, adding Sanders "was sore last week in his heel area and he felt great today."

Sanders' injury was the latest blow to a team that's lost seven starters from its opening-day lineup, including six on offence.

"It hurt, especially with an Achilles injury, that's a major injury," rookie receiver DaeSean Hamilton said. "He was our leader and he was a coach, too, so it was hard to watch."

Sanders' injury came three days after the Broncos lost star cornerback Chris Harris Jr . to a broken right lower leg, an injury that could sideline him for the rest of the regular season.

Sanders crumbled to the grass in an area of the field that has several brown patches and has led to several slips over the last few weeks, notably by rookie receiver Courtland Sutton.

Normally, the Broncos flip their two main practice fields from a north-south configuration to east-west at midseason, but they didn't do that this year. Nor did they rotate individual drills, leaving bare patches in several areas.

Asked if he thought field conditions played any role in Sanders' injury, Joseph said, "I don't, no. The fields are fine."

Sanders' injury amplifies odds the Broncos face in their quest to reach the playoffs for the first time in the post-Peyton Manning era. After surviving the league's most arduous schedule through November, the Broncos' next three opponents — 49ers, Browns and Raiders — are a combined 9-26-1. They finish the season in Denver against the Chargers, a team they beat last month.

"We can't cry about it," Joseph said. "We have to move on and go play a football game on Sunday."

Winners of three straight, the Broncos (6-6) visit San Francisco (2-10) this weekend.

The Broncos traded top receiver Demaryius Thomas to the Texans on Oct. 30 for financial reasons and to accelerate Sutton's growth by getting him into the starting lineup opposite Sanders. After flashing in training camp, Sutton has taken his lumps as a rookie. He has 28 receptions — but it's taken 59 targets — for 558 yards and three touchdowns.

Now, he'll face No. 1 cornerbacks beginning with Richard Sherman in San Francisco.

"I love it," Sutton said. "I look forward to it. It's going to be good."

Sanders developed a rapport with his new quarterback as soon as Case Keenum arrived in March, and the speedy receiver's leadership only grew in value when Thomas was traded.

Sanders helped bring along the young receivers simply by grabbing attention away from them, Keenum said, pointing to a 30-yard TD catch by Sutton in the Broncos' 24-10 win over the Bengals last weekend.

"Sometimes you run routes to get open and sometimes you run routes to get other guys open," Keenum said. "The touchdown pass, the route may have been designed this past week for (Sanders), but just the way they covered him up allowed Courtland to be 1 on 1 on the outside."

Aside from Holmes, who has 15 touchdowns in 91 career games for the Bills, Cowboys and Raiders, the Broncos' remaining receivers — Sutton, Hamilton, River Cracraft and Tim Patrick — boast a combined eight NFL starts with 37 catches for 692 yards and four touchdowns.

"I have all the trust in the world in those other guys," Keenum insisted.

The Broncos' best player on offence has been undrafted rookie running back Phillip Lindsay , who was the AFC's offensive player of the week for his 157-yard, two-TD performance at Cincinnati.

To prevent defences from stacking the box to stop Lindsay, offensive co-ordinator Bill Musgrave may have to relent and use Lindsay, along with running back Devontae Booker, more in the passing game.

Keenum would be all for that.

"We all know what Phillip can do with the ball in his hands in space," Keenum said. "So, I think all of those backs — Royce (Freeman), too — they're doing a great job of continuing to build their craft and not just being guys that run the ball between the tackles."

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