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After playing like one of baseball’s best players following a June 24 cortisone shot for his then-ailing right shoulder, Nationals third baseman Ryan Zimmerman is expected to receive another injection before Wednesday’s first game, Nationals Manager Davey Johnson said. Zimmerman, however, still faces the prospect of arthroscopic surgery in the offseason to clean up his right shoulder.

While his performance hasn’t shown any recent dips, Zimmerman is receiving another his fourth cortisone shot of the season, this time from team doctor Wiemi Douoguih, because the discomfort in his shoulder has bugging him again.

“It’s not near as serious as it was first time around,” Johnson said. “… He’s playing great, as far as I’m concerned. But the results from the last time we did it were so good and he felt so much better.”

This time, Zimmerman sought out the cortisone shot before it affected his performance and caused a slump. Before his miraculous shot in late June in Baltimore led to a dramatic turnaround in his season, Zimmerman played through the pain until he was a liability in the lineup.

“I think the difference between this one and the one in Baltimore is he wants the cortisone shot now, because he’s feeling it a little bit,” General Manager Mike Rizzo said. “In Baltimore, he needed it to perform up to his standards. There’s a big difference.”

The Nationals dealt with a scourge of injuries to key players this season and this week they faced the prospect of not playing with valuable infielder Danny Espinosa and slugger Michael Morse deep in a pennant race. Morse has been dealing with a bone bruise and returns Wednesday after missing four games. Espinosa received good news Tuesday when a second MRI revealead a bone bruise in the capsule of his left shoulder; he received a cortisone shot on Monday.

“I think in Morse and Espinosa’s cases, they’d want to play, and they’re perfectly capable of playing,” Rizzo said. “ …The decision you make at this time of the year versus if you weren’t in the playoff chase, would be does the injury or what you do to help the injury, is that going to cause further harm, or is there no further harm you can cause? In both these cases, no further harm can be caused by taking the steps that we are. So we would take these steps no matter where we were.”

For Zimmerman, the plan all along was to give him shots to ease the inflammation in his AC joint as needed, but it was understood that it could lead to offseason surgery. Surgery was discussed when Zimmerman received his second shot in June and was again brought up this week. Zimmerman said in June that if the inflammation continued to plague him, he would rest for a month after the season and determine if he needed surgery. If he did opt for surgery, he said it would be a benign procedure to remove the little bone chips and it would shut him down for possibly four to six weeks.

“It’s a possibility,” Rizzo said. “It would just be a short clean-up with a short rehab, and certainly he’d be ready for spring training.”

Zimmerman, in the first season of his six-year, $100-million extension, received two cortisone shots in mid-April when the inflammation in his throwing shoulder first appeared and he missed 13 games on the disabled list. But the rest and shots didn’t ease enough of the pain, and Zimmerman struggled through the worst and longest slump of his career. He was hitting .218 with only three home runs, his power and bat speed sapped by the discomfort.

Zimmerman received the third shot of the season roughly an hour before a June 24 game in Baltimore and instantly felt relief, notching two hits that day and beginning on one of baseball’s hottest tears. He hit 10 home runs in July, and since that June shot, Zimmerman hit .332 (100 for 301) with 19 home runs and 62 RBI in 75 games since. It was a drastic turnaround that Zimmerman credited to feeling healthy.

“It was one of those things where I didn’t want to play but I knew I was banged up but I was good enough to play,” he said last week. “You kind of compound that with struggling a little bit and it kind of snowballed. That was about as tough a six-week stretch as I’ve ever had in my career. To be able to look up there now and know I’ve been able to battle back from that, and more importantly, can actually help the team win now, I’m pretty proud of it.”