The Pittsburgh Pirates are a win away from their second 90-win season in three years after going 20 in a row without reaching that mark. Overcoming their drought of division titles has been more difficult, but it's still not out of the question.

The Pirates enter the second-to-last week of the season four games back, and while they don't play the NL Central leaders for another week, a four-game series in Colorado beginning Monday night could help them trim the gap before then.

After Sunday's 4-3 road win, Pittsburgh (89-56) took two of three against the Los Angeles Dodgers over the weekend to gain a game on St. Louis in the division and remain two ahead of the Chicago Cubs for the top wild card.

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The Pirates, who haven't won a division title since 1992, also won two of three at home over the Rockies from Aug. 28-30, but former Rockies manager Clint Hurdle is 5-7 at Coors Field dating to his first season with Pittsburgh in 2011.

"What we've done in the past has no influence on what we do now. But it has been challenging," Hurdle told MLB's official website.

The club's magic number to clinch a playoff spot is three, so Hurdle could wrap up a postseason spot at the ballpark in which he managed a World Series.

Road wins haven't been hard to come by at Coors, though the Rockies (63-86) did take two of three there from San Diego over the weekend. It was their first home series win in their last seven while going 9-14 since the start of August.

Pittsburgh begins the series by handing the ball to A.J. Burnett, who hasn't earned a decision in two starts since returning from six weeks on the disabled list with elbow inflammation.

The Pirates have lost his last four starts with the right-hander going 0-2 with a 7.52 ERA. Burnett (8-5, 3.15 ERA) hasn't made it through six innings in any of them after completing at least six in his previous eight starts.

He gave up two runs and eight hits in 5 1-3 innings of Wednesday's 3-2 home loss to the Cubs and recognizes there's still progress to make.

"I need to throw more first strikes to certain hitters," Burnett said. "But, otherwise, I'm getting there. I threw some good pitches."

Burnett hasn't faced the Rockies since 2013 and is 3-4 with a 3.18 ERA in seven starts against them. In two outings at Coors, though, he's allowed 11 runs in 12 1-3 innings. The veteran has held Jose Reyes to a 5-for-27 showing in their matchups, but the shortstop is batting .345 in 20 games in Colorado since being acquired from Toronto on July 27.

The Rockies counter with Jon Gray, who's still after his first major league win. Gray (0-1, 5.00) suffered his first loss in last Monday's 4-1 defeat against the Dodgers. The rookie gave up two runs and six hits with a personal-best eight strikeouts in 4 2-3 innings while throwing a season-high 92 pitches.

"I saw explosive fastballs," manager Walt Weiss said. "And his secondary stuff was good. He threw some sliders, some good changeups. That's a tough lineup to get through. He did a real nice job keeping us in position to win that game."

The right-hander also failed to make it five innings in a 5-3 loss in Pittsburgh on Aug. 28, surrendering three runs and seven hits in 4 1-3 innings with Andrew McCutchen going 2 for 2 and Gregory Polanco 2 for 3.

At Coors, Gray has a 7.88 ERA and .391 opponent batting average in four starts.