Tyler Anderson was just 19 pitches into his big-league career Sunday when the middle of a Padres’ lineup that has wrecked the Rockies this season put two runners on. Melvin Upton Jr. came to the plate.

Anderson’s mind, if not his heartbeat, raced. Within the previous 24 hours he had been called up from the minor leagues then told, surprisingly, that he would start the next day against San Diego. And his debut could have ended in a flash.

“There were times when things were going fast, and I had to step off and say, ‘OK, wait, I want to throw this as hard as I can. But really, what should we be doing? What’s the smart play?’ ” Anderson said. His 80-mph changeup forced Upton to ground out.

The Rockies, like their rookie left-hander, are figuring it out as they go. Over a stretch of playing on 27 consecutive days, Colorado’s rotation was ruffled. The club shuffled starters and long-relievers and plugged holes with veterans and young arms as best it could.

What’s left for the Rockies — with an East Coast road trip and a home series against Toronto and Troy Tulowitzki coming in the next two weeks — is a collection of starting pitchers that don’t all fit into a five-man rotation.

Anderson’s arrival, and his impressive debut in the Rockies’ 2-1 victory Sunday, gives manager Walt Weiss seven starting pitchers. And another top prospect, Jeff Hoffman, is headed toward a call-up.

“We’ll figure it out,” Weiss said. “We have some things to shuffle around.”

Jorge De La Rosa, who was banished to the bullpen last month, re-enters the starting rotation Tuesday to face the New York Yankees at Coors Field. Chad Bettis, who hasn’t made it through the fifth inning since May 17, will go Wednesday. Rookie Jon Gray, with 19 strikeouts and one walk in his past two games, likely will start Friday at Miami against Jose Fernandez. Tyler Chatwood, the ace, will start next weekend.

Chris Rusin, who quietly has been the Rockies’ third-best pitcher during the past two weeks, will skip his next start. Eddie Butler, who was ready in the bullpen Sunday, could move to the long-relief role vacated by De La Rosa.

And Anderson earned another shot at a start. He gave up just one run in 6⅓ innings.

“Talk about a tough assignment, coming in to pitch like that,” Weiss said. “He pounded the zone. He had all his weapons working. What a debut. We thought highly of this kid for a long time. The way he handles himself. He thinks at a different level. It’s all paying off.”

Anderson pitched like a veteran Sunday. The 26-year-old, who less than a month ago made his season debut in Double-A, showed outstanding fastball command and a confident slider. He didn’t walk a batter.

His rise to the Rockies took him through three starts in Triple-A, where he pitched next to Hoffman, the right-hander acquired from Toronto in the Tulowitzki trade last July. Hoffman has excelled in 12 starts for Albuquerque, with a 3.49 ERA and a team-high 63 strikeouts.

“We don’t talk about the stuff,” Isotopes pitching coach Darryl Scott said. “Everybody knows what kind of stuff he has. He’s getting away from that mindset of just trying to out-pitch a lineup but executing instead.

“If stuff gets you to the majors, it won’t keep you there.”

The Rockies are stuffing their big-league roster with young starters. The results so far are mixed. By park-adjusted statistics, their pitching ranks middle-of-the-pack in the National League. And Colorado is 30-33, 7½ games behind division-leading San Francisco.

But decisions are looming.

“I learned my first year in pro ball that you really can’t force anybody’s hand on any decisions,” Anderson said. “If you start focusing on where you want to be, instead of pitching every day and playing for your teammates, things will fall to the wayside real quick.”

Juggling a rotation

The Rockies have seven available starting pitchers, which will require some shuffling to the rotation soon:

RHP Tyler Chatwood

Has moved to the front of the rotation, with eight victories and a 2.89 ERA. He’s a legitimate All-Star candidate.

LHP Jorge De La Rosa

Demoted to the bullpen last month but moved back to the rotation after four strong innings last week. He starts Tuesday against the Yankees.

RHP Chad Bettis

Has struggled in his past four starts and appears fatigued at times. Might be pitching for his job in the rotation Wednesday.

RHP Jon Gray

The rookie is rolling, looking like a potential future staff ace. And the chains are off. He has no immediate pitch or innings restrictions.

LHP Chris Rusin

Started the season as a long reliever then moved into the rotation to replace De La Rosa. His start was skipped this week.

RHP Eddie Butler

His scheduled start Sunday was turned into a bullpen assignment. He was insurance in case rookie Tyler Anderson needed a long reliever.

LHP Tyler Anderson

Impressed in his major-league debut, allowing just one run in 6⅓ innings. He likely earned another start, even in a crowded rotation.