Barring any setbacks, he would likely be activated Saturday as the allotted 26th man for the A's scheduled doubleheader in Tampa. Doolittle has missed 34 games with a shoulder strain.
"Each time he's felt better, and we're comfortable with three [rehab outings]," A's manager Bob Melvin said, "so if all goes well he'll be back with us on the road."
Doolittle "felt really good" in Stockton on Monday, per Melvin, throwing nine of his 14 pitches for strikes en route to whiffing the side in order.
"Can't get better than that, right?" Melvin said.
Doolittle had a 3.52 ERA with 11 strikeouts across 7 2/3 innings in nine games before hitting the DL.
• Right fielder Matt Joyce was held out of Tuesday night's lineup with a minor left quad strain. Joyce will likely be rested through Thursday's off-day, though he could potentially be available off the bench for Wednesday's series finale with Toronto.
Outfielder Khris Davis, meanwhile, was limited to DH duties Tuesday, after departing Monday's game with left calf soreness.
• Infielder/outfielder Matt Olson was optioned to Nashville to make room for Tuesday starter Jesse Hahn. Olson, recalled just Saturday, appeared in one game, drawing a bases-loaded walk as a pinch-hitter Sunday.
Jane Lee has covered the A's for MLB.com since 2010.