Robbie Erlin's last appearance on a major league mound came in the 2014 season finale.

The San Diego Padres have played 148 games in 2015, and Erlin's outing remains the last time they've handed the ball to a left-handed starter.

That'll change Saturday night when Erlin makes his season debut in Denver against the Colorado Rockies, who coincidentally have had their problems against lefties.

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Erlin made 20 starts and four relief appearances for the Padres (69-79) over the previous two seasons, going 7-8 with a 4.58 ERA. He made the opening-day roster in 2014, missed nearly four months with an elbow injury suffered last May and made four starts after returning, the last of which he threw just 1 2-3 innings in a loss to San Francisco.

Since then, Erlin has spent his time in the minors and battled shoulder soreness earlier this season. San Diego plans to use him in the rotation for the rest of 2015 after he pitched a seven-inning, complete-game shutout Sept. 5 at Reno his last minor league outing.

"I'm just happy to be back and hope to make the most of the experience and the time here," Erlin, who had a 5.60 ERA in 24 starts for the Chihuahuas, told MLB's official website.

Now Erlin has to contend with a Rockies lineup that features Nolan Arenado and Carlos Gonzalez, who have the second- and third-most homers in the NL, respectively.

Neither homered Friday, but Arenado went 3 for 4, drove in a run and scored twice as Colorado (62-85) beat the Padres 7-4. Arenado is batting .365 with nine of his 39 homers in 18 games this month, and the third baseman also made a nifty play in the field when he bare-handed a bunt and fired to first for the out.

''(He) changes the game with his defense virtually every night," manager Walt Weiss said. "That doesn't seem to carry any weight in MVP voting - don't know why.''

Arenado is hitting .390 with six homers and a 1.139 OPS in 15 games against the Padres this season.

''I'd probably vote for him (for MVP),'' San Diego interim manager Pat Murphy said.

The Rockies, though, are just 8-28 when their opponent starts a left-hander. Gonzalez is batting .181 with four of his 37 homers against lefties this season compared to having a .294 average against right-handers.

The Padres (.243) haven't hit much better off lefties than Colorado (.242), which counters with a left-hander of its own in Yohan Flande (3-3, 4.95 ERA).

Flande, though, hasn't recorded an out beyond the fifth in any of his last four starts while walking 11 in 18 innings. He's especially struggled over his last two, giving up six runs in a 7-4 loss to San Francisco on Sept. 6 and four in last Saturday's 7-2 defeat at Seattle.

He's had his issues against San Diego as well, going 0-2 with a 5.63 ERA in three starts. Flande allowed four runs in six innings of a 9-5 loss when he last faced the Padres on Aug. 14.

Matt Kemp is 4 for 6 with a homer off Flande, but he went hitless in four at-bats Friday and is 2 for 23 over his last six.

The Padres have lost six of their last eight, a stretch that began with a home loss to the Rockies on Sept. 10.