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Philadelphia Phillies outfielder and two-time NL MVP Bryce Harper is ready to hit in games as he progresses with his rehab from Tommy John surgery, manager Rob Thomson told NBC Sports Philadelphia on Tuesday. Harper has not yet been cleared to slide, however, which is the next rehab hurdle he must clear.

Here's more from NBC Sports Philadelphia:

Sliding is what's holding back his return. Phillies manager Rob Thomson said Tuesday that Harper would be ready to hit in a game today, but again emphasized the risks associated with sliding. One false move could result in his ulnar collateral ligament rupturing again.

"Once he gets on base, then we can put a brace on him," Thomson said. "But if he hits a double, we can't hand a brace off to him as he's rounding first base. That's really where it gets dangerous."

Telling Harper to not slide to hasten his return is not practical. Sliding is instinctual and ingrained in a player's muscle memory, plus Harper tends to run the bases aggressively. There's also the risk of slipping or stumbling on the base paths, and reinjuring the elbow on a fall. Rushing back from Tommy John surgery often leads to a setback.

Harper has been hitting against high velocity and breaking balls off a pitching machine in the batting cage, and he's also taken ground balls at first base. That does not necessarily mean Harper will play first base when he returns (though the Phillies are down their top two first base options). Ground balls are the first step back on the defensive side for injured players, even outfielders.

The 30-year-old Harper had Tommy John surgery in November and the usual rehab timetable for position players puts him on track to return sometime around the All-Star break. The Phillies declined to put Harper on the 60-day injured list to begin the season, leaving open the possibility he could return before the end of May.

Harper hit .286/.364/.514 with 18 home runs in 99 games around a broken thumb last season, and he did not play the field after April 16 because of the elbow injury. He slashed .349/.414/.746 with six homers in 17 postseason games during Philadelphia's run to the National League pennant.