Alexander will serve as the Rays' bulk reliever Sunday against Arizona, Marc Topkin of the Tampa Bay Times reports.

Tampa Bay recalled Alexander from Triple-A on Saturday in the wake of Zack Littell's (shoulder) move to the 15-day injured list. While Alexander won't officially start Sunday's contest, he'll be the Rays' primary pitcher behind opener Drew Rasmussen. Alexander has allowed two runs across his last four big-league appearances, racking up 15 strikeouts across 14.1 innings.

Rasmussen will serve as the Rays' opening pitcher for Sunday's game against Arizona, Marc Topkin of the Tampa Bay Times reports.

Rasmussen will make his second start of the season Sunday, though he's expected to pitch just one or two innings before handing the ball off to bulk reliever Tyler Alexander. Since completing his recovery from an internal brace procedure and returning from the 60-day injured list Aug. 7, Rasmussen has given up three earned runs on six hits and no walks while striking out six over five innings.

Slaten (elbow) is scheduled to throw a bullpen session Monday and start a minor-league rehab assignment shortly thereafter, Ian Browne of MLB.com reports.

Slaten will incorporate an up and down into Monday's bullpen before embarking on what's expected to be a brief rehab assignment. The 26-year-old has been on the shelf since July 12 due to elbow inflammation. The issue wasn't expected to sideline Slaten for more than the minimum 15 days, but his recovery was thrown off schedule by an illness.

Webb (elbow) played catch Saturday, Jacob Calvin Meyer of The Baltimore Sun reports.

Webb has been on the shelf since Aug. 7 due to elbow inflammation and Saturday appears to be the first time he's played catch since. Initial indications were that Webb wouldn't need to miss much more than the minimum 15 days, but he seems to be at least a week or two away from returning.

The Angels activated Cisnero (shoulder) from the 60-day injured list Saturday, Erica Weston of Bally Sports West reports.

Cisnero hasn't pitched for the Halos since April 27 due to inflammation in his throwing shoulder. However, after allowing one run with eight strikeouts across four rehab appearances (4.2 innings) with Triple-A Salt Lake, the 35-year-old was cleared to rejoin the active roster. Jose Soriano (arm fatigue) was placed on the 15-day injured list in a corresponding move.

The Astros recalled Martinez from Triple-A Sugar Land on Saturday, Matt Kawahara of the Houston Chronicle reports.

He'll provide a fresh arm to the Houston bullpen after Ryan Pressly was placed on the 15-day injured list in a corresponding move due to a lower-back strain. Over his 41 appearances with Houston before he was optioned to Sugar Land on July 31, Martinez posted a 2.92 ERA and 1.22 WHIP across 49.1 innings.

The Astros placed Pressly on the 15-day injured list due to a lower-back strain, Matt Kawahara of the Houston Chronicle reports.

It's unclear when exactly Pressly sustained the strain, but he's given up one earned run in each of his last four outings. In his 10 outings since the All-Star break, he's recorded six holds and two blown saves with a 4.50 ERA and 1.80 WHIP over 10 innings. Seth Martinez was recalled from Triple-A Sugar Land in a corresponding move.

The White Sox placed Wilson on the 15-day injured list due to a lower-back strain.

Wilson has appeared in 10 games since being recalled by the White Sox after the All-Star break, allowing 13 runs (12 earned) on 11 hits and nine walks while striking out eight across 8.2 innings. Gus Varland was recalled from Triple-A Charlotte in a corresponding move.

The White Sox recalled Varland from Triple-A Charlotte on Saturday.

Chicago placed reliever Steven Wilson (back) on the 15-day injured list in a corresponding move. Varland was claimed off waivers by the White Sox on Aug. 2 after being designated for assignment by the Dodgers three days prior. He has a 3.00 ERA and 1.83 WHIP across six major-league innings this season.

The White Sox claimed De Los Santos off waivers from the Yankees on Saturday.

De Los Santos will move on to his third team in less than a month, as the Padres traded him to the Yankees on July 30 before he New York designated him for assignment Wednesday. Though he was moved off the Yankees' 40-man roster after giving up seven earned runs in a 1.2-inning relief appearance against this same White Sox squad, Chicago evidently felt that De Los Santos' stronger body of work over parts of six big-league seasons made him worthy enough for a spot in the bullpen. Since he doesn't have minor-league options remaining, De Los Santos will report to the big club.