MLB.com's Jesse Sanchez confirms Casey Kelly will make his major league debut Monday against the Braves.

An expected move, but it's now official. Kelly owns a 3.78 ERA over his first 73 pro starts and will replace Jason Marquis (wrist) in the Padres' starting rotation. The 22-year-old will be the 15th pitcher to start a game for San Diego this season.

Casey Kelly is expected to make his major league debut Monday against the Cardinals.

Kelly has missed the majority of this season with an elbow injury, but is 0-1 with a 3.78 ERA in three rehab starts with Double-A San Antonio. Look for him to take the place of Jason Marquis (wrist) as the Padres' fifth starter.

Padres pitching prospect Casey Kelly (elbow) will move up to Double-A San Antonio for his next start.

Kelly, who is working his way back from right elbow soreness, made three appearances for the team's rookie-level club in Arizona. He should be promoted to Triple-A Tucson before the end of the season.

Padres' prospect right-hander Casey Kelly (elbow) has progressed to throwing from 120 feet without pain.

Kelly has been shut down since mid-April with elbow soreness. While he experienced a minor setback earlier this month, the Padres are hoping he'll be game-ready by July 1.

Casey Kelly had his elbow examined in San Diego Monday after experiencing renewed soreness.

It's not clear at this point what the exam revealed. An MRI last month on Kelly's elbow revealed no structural damage, but clearly there's something going on in there. We'll update his status when more is known.

An MRI taken Tuesday on prospect Casey Kelly's right elbow showed no structural damage.

The 21-year-old right-hander only has inflammation and should be back on track within a month. Kelly has yielded three runs in 12 innings this year at the Triple-A level, striking out 14 while walking none.

Padres' pitching prospect Casey Kelly traveled to San Diego to have his right elbow examined.

Kelly dealt with some elbow soreness after his last start, so the Padres obviously aren't going to take any chances. The 21-year-old right-hander has allowed three runs over 12 innings in his first two starts with Triple-A Tucson this season while striking out 14 and walking none.

Padres reassigned RHP Casey Kelly to minor league camp.

No surprise here. Kelly, of course, was the big get in the Adrian Gonzalez trade back in December. The 21-year-old right-hander is one of the most promising pitching prospects in all of baseball, though we likely won't see him in the majors until 2012. Left-handers Colt Hynes and Rob Musgrave were also reassigned to minor league camp while outfielder Cedric Hunter was optioned to Triple-A Tucson.

Corey Brock of MLB.com has been told that new Padres prospect Casey Kelly is unlikely to log more than 150 innings this year.

Kelly, 21, was the centerpiece of December's Adrian Gonzalez trade and projects as a front-end starter. He spent most of the 2010 season at the Red Sox's Double-A affiliate in Portland, Maine, posting 81 strikeouts and only 35 walks in 95 innings of work. The Padres seem likely to get him started at their own Double-A affiliate and he could move quickly to Triple-A. The rumored innings limit will probably prevent him from being a September call-up.

Padres acquired RHP Casey Kelly, 1B Anthony Rizzo, OF Reymond Fuentes and a PTBNL from the Red Sox for 1B Adrian Gonzalez.

Quite a haul for the Padres, who weren't planning on re-signing Gonzalez after the 2011 season anyway. Kelly, 21, registered 81 strikeouts in 95 innings this year at the Double-A level and went on to pitch well in the Arizona Fall League. He projects as a quality big league starter and has now joined a club that plays in one of the game's more pitcher-friendly parks.

Red Sox pitching prospect Casey Kelly finished with a 6.75 ERA over four starts in the Arizona Fall League.

Kelly actually pitched pretty well in three of his four outings, but he was torched for eight runs in a fluky two-inning start last Monday. The 21-year-old righty averaged a stellar 7.7 K/9 over 21 appearances this year at Double-A Portland and remains a top pitching prospect. With a little polishing, he should be a high-impact big league starter for a long time.

Red Sox prospect Casey Kelly allowed eight runs in a two-inning start Monday in the Arizona Fall League.

Kelly threw only 28 of his 46 deliveries for strikes, and the pitches that did cross the plate were handled easily. The 21-year-old did really well in his first two AFL outings and is still in recovery mode from a strained right latissimus muscle in his back. It seems like he simply had an off day. Kelly averaged a solid 7.7 K/9 in 21 starts with Double-A Portland this season.

The Red Sox have shut down prospect right-hander Casey Kelly for the rest of the season due to a strained right latissimus muscle in his back.

It's being called precautionary, as the team decided not to rush Kelly through rehab in order to make just one or two more starts this season. The team plans to pitch him in a fall or winter league, instead. The 21-year-old right-hander went 3-5 with a 5.31 ERA in 21 starts with Double-A Portland this season, averaging 7.7 K/9 and 3.3 BB/9.