OAKLAND -- Left-hander Darren Oliver was activated from the 15-day disabled list before the Angels' game against the Oakland Athletics on Monday night.

It's the first step in what manager Mike Scioscia hopes becomes a steady stream of returning hurlers.

Right-hander Kevin Jepsen was also activated and optioned to Triple-A Salt Lake. He'll be joined by right-hander Fernando Rodriguez, who was sent down to make room for Oliver.

"We'll still evaluate him on a night-to-night basis to where Darren slots in," Scioscia said. "Some nights we can use him later in the game. For now, we'll just get him an inning or two. He feels strong."

Oliver went on the DL with a strained left triceps after pitching four innings in a start against the Minnesota Twins on April 18. He's been effective in his three appearances this season, allowing two runs over 7 2/3 innings. He's struck out four and walked two.

The week begins with hope for the pitching staff. In addition to Oliver, right-hander Ervin Santana threw his first rehab assignment with Class A Rancho Cucamonga, lasting 4 2/3 innings. He gave up three runs on four hits, striking out three with no walks. He gave up two home runs.

Right-hander John Lackey is slated for his first rehab appearance on Tuesday with Salt Lake.

"If they can build up to 90 pitches, it would be enough to consider having them come back to rejoin the rotation," said Scioscia. "They'll each have at least two more starts."

Right-hander Dustin Moseley, on the DL with right elbow irritation, has been throwing long toss on flat ground and could pitch a bullpen session when the Angels return to Anaheim on Wednesday.

Right-hander Kelvim Escobar has been throwing off a mound and could also be nearing a rehab assignment.

Scioscia indicated the pitching staff could be at full strength in two to three weeks.