Rookie right-hander Collin McHugh makes his major-league debut with the New York Mets Thursday when they host the Colorado Rockies in the finale of a four-game series at Citi Field.

The 25-year-old Georgia native gets the call in place of former ace lefty Johan Santana, who was placed on the 15-day disabled list with back problems that have been plaguing him all season.

An 18th-round pick of the Mets in the 2008 draft, McHugh spent his initial three pro seasons at Single-A before climbing the ladder to Double-A in 2011.

He's made 12 starts apiece this season at Double-A and Triple-A, combining to post a 2.88 earned run average with 132 strikeouts in 143 2/3 innings.

In five seasons in the minors, he's struck out 520 batters in 521 innings.

McHugh is opposed by fellow youngster Tyler Chatwood, who makes his fifth start of the season and 30th in his career.

The 22-year-old was 6-11 in 27 appearances - 25 starts - with the Los Angeles Angels of Anaheim last season before he was sent to the Rockies in a November deal that sent Chris Ianetta to the Angels.

He began this season with seven straight relief appearances and was 1-2 with a save and a 7.62 ERA, but has since gone 2-2 in four starts.

He's defeated San Francisco and Milwaukee while allowing just two runs on seven hits in 11 innings, but lost decisions to the Giants and Miami while giving up 11 hits and nine runs in 7 1/3 innings.

Chatwood won his lone career meeting with the Mets after allowing four hits in seven scoreless innings with four walks and four strikeouts.

On Wednesday, Wilin Rosario belted the tie-breaking solo home run in the seventh inning, as the Rockies continued their domination of the Mets with a 5-2 victory.

Tyler Colvin had two hits and scored twice for the Rockies, who will aim for a four-game sweep Thursday afternoon. Colorado, which has won four in a row and eight of its last 10 contests, has won seven road games against the Mets.

Scott Hairston and Ike Davis each knocked in a run for the Mets, who have been held to two runs or less in five consecutive contests, their longest stretch since Sept. 15-19, 2003.

"Each one of us is going out and taking our jobs seriously. We don't take it lightly," Hairston said. "We play our hearts out. Our best wasn't good enough today."

Colorado lost center fielder Dexter Fowler with a sprained right ankle. He was hurt in the fourth inning.

The Mets won two of three games from the Rockies in April in Denver, while the Rockies won five of seven between the teams in 2011.