Millwood makes his final start of the season when the Rockies try to split their four-game series with the major league-worst Houston Astros on Sunday.
After losing a season-high nine straight to fall 17 below .500 for the first time since 2008, Colorado (71-87) won 4-2 in 13 innings Saturday in the 200,000th game in major league history.
The Rockies will look to win two straight for the first time since Sept. 10-11, with Millwood (3-3, 4.56 ERA) trying to rebound from his worst start since signing with the team Aug. 10.
The 36-year-old right-hander went 4-16 with a 5.10 ERA for Baltimore last season before signing minor league deals with the New York Yankees and Boston earlier this year. He has quieted some of the talk that he may be finished with a solid seven-week stretch with the Rockies.
Millwood wasn't very good his last time out, though, surrendering a season-high seven runs in a season-low 3 1-3 innings of an 8-2 loss to San Diego on Monday.
"It was a bad night,'' Millwood said. "I pitched bad.''
The veteran has gone 5-2 with a 3.15 ERA in eight starts at Houston, the most recent one coming June 26, 2008, while with Texas.
The Astros (55-103) continue a season-ending seven-game homestand with Lucas Harrell (0-1, 2.00) on the hill.
The right-hander, acquired off waivers from the Chicago White Sox in July, has made his last three appearances out of the bullpen. He'll make his second start with the club with Bud Norris out due to biceps tendinitis.
Getting a spot start in place of Brett Myers on Sept. 2, Harrell tossed 5 1-3 shutout innings in an 8-2 loss to Milwaukee in his Astros debut. It was the first time a Houston pitcher threw that many innings of shutout ball in his club debut since J.A. Happ went six against the Brewers on July 30, 2010.
"He really battled," manager Brad Mills told the Astros' official website about Harrell, who went 5-2 with a 1.72 ERA in nine starts for Triple-A Oklahoma City. "The foul balls really upped his pitch count (career-high 114), but he really battled well."
Harrell has never faced the Rockies.
The Rockies have dropped seven of 10 at Houston.