DENVER -- The Pirates rallied late, but the Rockies struck last.
Dexter Fowler hit a sacrifice fly with one out in the ninth inning to score Wilin Rosario in the bottom of the ninth as the Rockies beat the Pirates, 5-4, Monday night at Coors Field.
Pirates reliever Jason Grilli took the loss, his third of the season.
"Some days you're the hero, some days you're the goat," Grilli said. "It's kind of weird to have a night like this. Stings pretty good."
Rosario led off the inning with a single to left field and advanced to third when Jason Giambi singled to right-center with one out.
Pedro Alvarez tied the game in the top of the ninth inning with a three-run homer on the first pitch after a 53-minute rain delay.
"You've got some momentum going, then they throw the tarp on. Then you've got to go out there and play," manager Clint Hurdle said. "One swing of the bat, and boom.
Alvarez smacked a 98-mph fastball off left-handed reliever Rex Brothers and parked it in the left-field seats for his 18th home run of the season, tying the game, 4-4. Alvarez said it is challenging to keep adrenaline going after a lengthy rain delay.
"It's tough because you've got to sit around for so long without doing anything," Alvarez said. "Then you have to resume play like nothing happened."
Andrew McCutchen and Neil Walker both singled against Rockies closer Rafael Betancourt before crew chief Gary Cederstrom called out the grounds crew onto the field with one out in the ninth.
It was eerily similar to the last time the Pirates were delayed on the road on Sept. 3, 2011, in Chicago. Then, Derrek Lee hit a grand slam to help the Pirates claw back from a late deficit in a 7-5 victory.
Only difference was, Lee's blast gave the Pirates the lead. Following Alvarez's blast, Rod Barajas singled, but Clint Barmes grounded into a double play to end the inning.
Starter Jeff Karstens pitched seven innings, allowing four earned runs on six hits -- four of which came in an ugly fifth inning. He struck out four and walked two, throwing 67 of his 101 pitches for strikes.
"The one inning was the one that got away from him," Hurdle said.
He was pleased Karstens was able to pitch so deep in the game -- something he wanted his starter to do after the lengthy break following the All-Star Game.
With the loss, the Pirates (49-40) missed an opportunity to gain any ground on the first-place Cincinnati Reds, who lost earlier in the night to the Arizona Diamondbacks, 5-3.
It marked the first time the Pirates have lost back-to-back games since they dropped the first two games of a series against the Philadelphia Phillies on June 25 and 26. It was also the third consecutive series-opening loss, after the Pirates dropped the first game in series against the Milwaukee Brewers and San Francisco Giants.
The Rockies (35-54) pounded Karstens for four runs in the fifth inning to grab a 4-1 lead.
Karstens allowed the first four runners to reach base in the inning, all of whom scored. He walked Tyler Colvin, allowed back-to-back singles to Rosario and Josh Rutledge, the second of which scored Colvin.
Eric Young Jr. belted a doubled off the base of the right-field wall, clearing the bases and giving the Rockies their first lead of the game. Two batters later, Marco Scutaro singled to left field, scoring Young.
Karstens faced eight batters and threw 24 pitches in the inning.
"It all started with a leadoff walk, something that can't happen," Karstens said. "It was one of those things where I put my team in a bad position."
He gave the Pirates a short-lived lead in the top half of the inning with his third career RBI. With two outs and Alvarez on third base, Karstens hit a high-bouncing grounder over Rockies first baseman Michael Cuddyer's head and into shallow right field, scoring Alvarez.
It was Karstens first RBI since July 5, 2011, when he drove in a run in a 5-1 victory against the Houston Astros.
Before Karstens got to the plate, Barmes put Alvarez in scoring position with a two-out single that dropped in front of a diving Carlos Gonzalez in left field, allowing Alvarez to scamper from first to third.
The three-hit inning was the last of the night for Rockies starter Jeff Francis, who threw just 72 pitches. But with two runners on in the bottom half of the inning, Rockies manager Jim Tracy sent Young to the plate to try to get Colorado's offense going.
Francis allowed six hits and one earned run over five innings. Though 30 of his 72 pitches were balls, he did not walk a batter.
After Francis left the game, Colorado right-handed reliever Josh Roenicke pitched three scoreless innings in which he allowed only two Pirates to reach base -- one by single and the other by walk.
The Pirates had a baserunner in three of the first four innings but could never string together more than one hit in an inning. Alex Presley singled to leadoff the game and moved to second on a passed ball but was stranded there. Walker singled to leadoff the second, and McCutchen singled with one out in the fourth. But both were caught stealing to limit the Pirates' offense early.
Karstens escaped a bit of trouble in the second inning. He allowed a one-out double to Cuddyer down the left-field line and walked Rosario with two outs to put runners on first and second. But Karstens got Josh Rutledge to fly out to left to end the threat and keep the game scoreless early.
Walker extended his hitting streak to 16 consecutive games, two shy of his career high 18-game hitting streak he set in 2010.
Michael Sanserino: email@example.com, 412-263-1722 or on Twitter @msanserino. First Published July 17, 2012 4:45 AM