SAN DIEGO -- Rockies rookie pitcher Drew Pomeranz's next scheduled start could be pushed back if the soreness that affected his work Friday night continues, manager Jim Tracy said Saturday afternoon.

Pomeranz was ineffective for three innings of a 9-5 loss to the Padres and complained of general stiffness and discomfort in his arm afterward. Usually capable of a fastball 94-95 mph, Pomeranz sat at around 88.

The Rockies have been using a four-man rotation in a paired pitching system since late June, but Pomeranz has yet to throw on three days' rest, like he would have to if he pitches Tuesday at Arizona on the team's normal schedule. Pomeranz was at Triple-A Colorado Springs when the system started and his four starts since returning to the Majors have happened to be on four days' rest. It's unknown how many days the Rockies would push back Pomeranz (1-5, 4.98 ERA) or who would take his place.

Pomeranz, 23, was icing his biceps Saturday and said he was still sore, but he hoped to throw a bullpen session Sunday.

Helton has good day in first Minors rehab game

SAN DIEGO -- Veteran first baseman Todd Helton went 2-for-2 with a walk and an RBI for Rookie-level Grand Junction on Friday in the first game of his rehab assignment for right hip inflammation.

Manager Jim Tracy said Helton will be evaluated after another rehab game on Saturday. He is eligible to be activated Tuesday at Arizona.

Friday's event was a big one for Grand Junction, which is hosting the Rockies' Pioneer League affiliate for the first time this season. Helton's appearance drew a crowd of 5,161.

Also, right-handed pitcher Jhoulys Chacin threw a 45-pitch simulated game on Saturday and could be ready for an injury rehab assignment. Chacin has been out with a nerve issue in his chest, and hasn't pitched since May 1.

Rosario continues to rest hurting ankle

SAN DIEGO -- Rockies catcher Wilin Rosario, who left Friday night's game after awkwardly twisting his left ankle, had the ankle heavily taped and was unable to play Saturday night against the Padres.

Rosario, 23, had been concentrating on handling low pitches to his glove side, but crossed up his mechanics on a Drew Pomeranz pitch in the dirt and tumbled. The Rockies called it a low-grade ankle sprain.

Before the game, Rosario was receiving tips on handling pitches from experienced catchers Ramon Hernandez and Wil Nieves, who is on the disabled list with turf toe in his right foot. He hoped to translate what he learned to the game.

"I was making a little adjustment, but something happened," Rosario said. "I tried to [stay in], but my ankle became really tight."

The club will assess Rosario's health Sunday. Nieves is due to return from the DL on Tuesday. Instead of leaving the club to join Colorado Springs on an injury rehab assignment, Nieves will hang around just in case he needs to be activated Tuesday in Arizona. If not, he'll join Triple-A Colorado Springs for regular at-bats in Minor League games.

Saturday, Hernandez started and Jordan Pacheco, the regular third baseman, was the backup catcher.