One of those players will be 21-year-old right-handed pitcher Mat Latos, who will officially be recalled from Double-A San Antonio for a start Sunday against the Rockies at PETCO Park.
Latos is considered to be San Diego's top Minor League pitching prospect.
In order to make room for Latos on the 40-man and 25-man active roster, the Padres designated pitcher Josh Banks for assignment.
Latos, who tossed a scoreless inning in Sunday's Futures Game in St. Louis, has risen quickly in 2009, going 3-0 with a 0.36 ERA with Class A Fort Wayne and then completely bypassing high-Class A Lake Elsinore for Double-A San Antonio.
Latos is 5-1 with a 1.91 ERA in nine starts for San Antonio with 46 strikeouts and nine walks in 47 innings. Opponents are hitting .192 against him.
Towers has hinted several times in the past month that Latos would arrive in the Major Leagues before rosters expand from 25 to 40 players on Sept. 1.
But Towers cautioned last month that the team is wary of Latos' workload. He's already pitched 72 1/3 innings this season, more than he pitched in any of his first two seasons (both, ironically, 56 innings).
"I just think he's still inexperienced," Towers said. "He's never thrown more than 55 innings [in one season]. Even though he's flat-dominated, if we bring him up, he could end with 150 or so innings. That's more than triple what he's used to."
That means, Towers said, that Latos could be shut down before the season ends as a safeguard against a heavy workload.
"To me, a good barometer is to no more than double the innings," Towers said.
Latos, who was selected by the Padres in the 11th round of the 2006 First-Year Player Draft and signed before the '07 Draft, spent part of Spring Training in Major League camp, a first for him.
"He was with us in Spring Training and is familiar with our coaching staff and a number of our players," Black said. "He has pitched well. His performance through this Minor League season has been outstanding."
He has impressed the Padres with both his maturity and his advancement as a pitcher.
"He's answered the call on everything we've asked him to do," Padres vice president of scouting and player development Grady Fuson said after Latos was promoted to San Antonio in May. "He's down in the strike zone, his velocity is great, his changeup is great. He's ready to be challenged."
Corey Brock is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.