Denver ? Clinton Portis strutted down the sideline, turned and flexed his muscles for the crowd and flashed a large gold belt that declared him the “Heavyweight running back of the world.”

Cocky? Sure. But the way Portis has been playing, it’s hard to blame him.

“Last two weeks, best back in the NFL,” Broncos tight end Shannon Sharpe said.

It’s hard to argue.

At a time when the Broncos have needed him the most, Portis is playing the best football of his short career. Last year’s NFL offensive rookie of the year has 553 yards and seven touchdowns in the past three games, helping the Broncos go from a nearly hopeless situation to the thick of the AFC West playoff race.

Against Chicago two weeks ago, he had 165 yards on 14 carries but didn’t score a touchdown in a 19-10 loss. He followed with 170 yards on a career-high 34 carries in a rainy win over Oakland.

The best of the bunch came Sunday against Kansas City.

Portis ran for 218 yards and a team-record five touchdowns, turning a close game at halftime into a 45-27 rout that moved the Broncos into a tie with Miami for the final AFC playoff spot.

How good was Portis? He had a team-record 188 yards in the second half and two of his touchdown runs — 59 and 53 yards — were more than Kansas City’s Priest Holmes (44 yards) had on 12 carries.

“I always admired Priest Holmes. I thought he was the best back in the NFL,” Portis said. “I felt like if I go out and outperform Priest Holmes in head-to-head competition, well, I can’t help but feel like I am the best back in the NFL.”

With 48 yards in the next three games, Portis will join Eric Dickerson and Edgerrin James as the only running backs to open their careers with consecutive 1,500-yard seasons. He has 2,960 yards his first two seasons, behind only Dickerson, James and Earl Campbell all-time.

Portis’ 218 yards against the Chiefs was the third-most in team history and just the sixth 200-yard game for the Broncos. It also was his fifth consecutive 100-yard game and his 14th in 16 games.

“If we end the season the right way, he’s going to be an MVP candidate,” Denver defensive end Trevor Pryce said.