The Colorado Rockies have not been left a thick margin for error in the race for the NL West's top spot.

A rough road trip has not helped the Rockies, who look to avoid a third straight setback on Tuesday night in the first of three straight meetings with the New York Mets.

Colorado has lost six of the first seven contests of this 10-game road trip and sits nine games under .500 at 52-61. Even worse, the Rockies now trail the Los Angeles Dodgers, winners of 15 straight on the road, by 11 games for first place in the division.

The Rockies dropped the rubber match of a three-game series with the Pittsburgh Pirates on Sunday, 5-1, and sit 9 1/2 games out of the league's second Wild Card spot.

Colorado did see Carlos Gonzalez return to the lineup on Sunday as he continues to battle a nagging sprained right finger. Gonzalez, hitting .302 with 70 RBI in 103 games this season, is tied for second in the NL with 26 homers, but has not gone deep in his past 10 games since a home run on July 20.

The Rockies would love to see Gonzalez find his power stroke tonight as they send Chad Bettis to the hill for his second career start. He goes in place of Tyler Chatwood, who had his start pushed back due to left hamstring tightness.

Bettis, a second-round pick of the Rockies in 2010, made his Major League debut on the road Thursday against the red-hot Atlanta Braves and was tagged for five runs on six hits and five walks in five innings of an 11-2 defeat.

The Braves jumped on the nervous right-hander early, as Justin Upton followed a Jason Heyward walk to begin the bottom of the first inning with a homer to straightaway center. It was one of two homers given up in the game by the 24- year-old Bettis.

"If we can push the results aside, then it's a great day," Bettis said of his major league debut. "It still is, but we've got a lot of work to do."

Bettis joined the Rockies rotation after going 3-4 with a 3.71 earned run average in 12 starts with Double-A Tulsa. He missed all of last season with a shoulder strain and has flashed a 96-mph fastball this season.

The Mets are not without their struggles, having lost four of five and seven of their past 10 games. They dropped the final two contests of their three- game weekend series versus the Kansas City Royals without All-Star third baseman David Wright, who landed on the 15-day disabled list Saturday because of a Grade 2 strain of his right hamstring.

Wright was hitting .309 with 16 homers and 54 RBI in 105 games this season.

It was a bit of an eventful off day for the Mets on Monday as they saw two of their players handed 50-game suspensions for their connection to the Biogenesis case.

Hit with the bans were minor leaguers Jordany Valdespin and Cesar Puello. Valdespin batted .188 with four homers and 16 RBI in 66 games with the Mets earlier this season before a demotion to Triple-A in mid-July.

Puello, meanwhile, is ranked as New York's sixth-best prospect by MLB.com.

The Mets turn to right-hander Jenrry Mejia on Tuesday, with the undrafted 23- year-old set to make his third start of the season and ninth of his career.

Mejia made his season debut on July 26 and won in Washington, logging seven scoreless innings while striking out seven. He then hurled another quality start at Miami on Wednesday, but lost a 3-2 decision after giving up three runs on six hits and a walk in six frames.

"He was behind in a lot of counts ... and got himself into trouble," Mets manager Terry Collins said.

Two of Mejia's 40 career appearances have come versus the Rockies, both in relief.

The Rockies have won eight in a row in New York, having not lost there since Aug. 12, 2010. They have swept back-to-back four-game sets at Citi Field.