Casey Kelly certainly lived up to his billing as the San Diego Padres' top-ranked prospect in his debut earlier this week.

The young right-hander looks to make it two wins in as many starts on Sunday afternoon as he takes the hill for the Padres' finale of a three-game series against the Colorado Rockies.

Kelly is a former first-round pick by Boston and was a key player obtained by the Padres in a deal that sent first baseman Adrian Gonzalez to the Red Sox on Dec. 6, 2010. He was ranked as San Diego's top prospect by MLB.com and made his debut with the Padres on Monday in a start against the Atlanta Braves.

The 22-year-old impressed with six scoreless frames in which he scattered three hits and two walks, striking out four to lead a 3-0 triumph.

"It was an unbelievable feeling and a dream come true," Kelly said of his debut.

Manager Bud Black was also left impressed.

"I thought he pitched with the fastball the whole game," Black said. "Fastball had good sink, he threw it in and out, good spots ... a nice debut."

While San Diego goes with youth, Colorado starts 31-year-old Jeff Francis, who has picked up a pair of wins over a five-start unbeaten streak.

Francis has allowed just a run over consecutive five-inning outings and beat the Los Angeles Dodgers on Monday. He was charged with three hits and a walk while striking out six in a scoreless outing that keyed a 10-0 win.

"It's a great game. You have to play good baseball against this team, dealing with this lineup," Rockies manager Jim Tracy said. "You cannot afford to give them unnecessary opportunities. Jeff Francis did a great job of not allowing any of this to happen."

The lefty is 5-4 with a 5.44 ERA in 17 starts this season, but allowed five runs in five frames the last time he faced the Padres on July 21. He did not factor into the decision, however, and is 6-13 over his career in this matchup with a 5.52 ERA.

Colorado evened this series on Saturday with a 9-1 victory that featured the first grand slam of Dexter Fowler's career. Tyler Colvin added a solo homer and three RBI as the Rockies avoided a third straight loss.

Jhoulys Chacin didn't waste the run support, allowing a run on five hits and two walks over seven innings in the win.

"He was unbelievable, that was the best I've seen him," Fowler said of Chacin's effort. "It was definitely a bright spot for us."

San Diego starter Edinson Volquez was touched for five runs on nine hits over 4 2/3 frames to suffer the loss, just San Diego's second in 12 games.

Will Venable drove in the lone San Diego run with a solo homer, his ninth longball of the season.

"This year we're seeing more of a consistent approach at the plate," Black said regarding Venable. "He's not really tinkering with his swing, and I think it's paid off over the majority of his at-bats."

San Diego is 8-6 against the Rockies this year and hasn't captured a season series against them since going 11-7 in 2005.