It’s do-or-die-time for the San Francisco Giants.

The Giants were tied with division rival Colorado for the NL wild-card berth at the start of September, but they had gone 5-7 this month heading into this week’s three-game set with the Rockies, which began Monday night.

While the Giants have slumped the last two weeks, the red-hot Rockies had posted a major league-best 10-3 record this month before arriving in San Francisco for the final three games between the two NL West contenders. The series began with the Giants 4.5 games behind the Rockies in the wild-card race.

Scoring runs has been a struggle for the Giants, who were averaging just 3.08 runs a game in September at the start of the series. As a team, they were hitting only .219. Among all big league clubs, only Tampa Bay ranked below the Giants in both categories during this stretch. And San Francisco’s .169 average with runners in scoring position was dead last in the majors.

The Rockies, on the other hand, ranked among the most productive offensive teams in September. The Giants, though, had the great equalizer for the series opener. After back spasms pushed back his next start nearly a week, ace Tim Lincecum returned to the mound on Monday and shut down the Rockies through seven innings in a 9-1 win. The right-hander fanned 11, and relievers Jeremy Affeldt and Bob Howry held Colorado hitless over the final two frames.

The biggest news of the night was the nine runs the Giants scored in the must-win matchup. It marked only the third time in 13 September contests that they have scored more than three runs. The outburst came a day after the Giants had scored seven times in Sunday’s victory over the NL West-leading Dodgers.

Leadoff Eugenio Velez came though with four RBIs on Monday, and both Juan Uribe and Travis Ishikawa have gone 5-for-8 over the last two games. Uribe has continued his hot hitting while Ishikawa has shown signs of breaking out of an extended slump. The pair scored seven of San Francisco’s 16 runs the last two days.

The gap is now 3.5 games. The Rockies go with their top starter on Tuesday, Ubaldo Jimenez, with the Giants calling on lefty Barry Zito. Wednesday’s matchup may favor the Giants, as Matt Cain takes the hill against Rockies southpaw Jorge De La Rosa.