NEW YORK -- An examination Thursday afternoon revealed that Mets left-hander Johan Santana is experiencing fatigue in his left shoulder. Remaining with the Mets in New York for the next week, Santana will continue to exercise but will not resume throwing until his symptoms subside.

The results of Santana's shoulder exam at the Hospital for Special Surgery were "otherwise normal," according to a team release. Even so, given that less than eight weeks remain in the season, the possibility of the two-time Cy Young Award winner returning to the Mets in September now seems slimmer than ever.

After undergoing surgery last September to repair a torn anterior capsule in his left shoulder, Santana began throwing a baseball in February before first stepping onto a mound in June. He pitched three scoreless innings in a rehab start last Thursday, beginning a sequence that put him on track for a late-August return to the Mets.

But several days after his outing, Santana complained of discomfort in his shoulder, prompting the Mets to cancel his Minor League rehab assignment and schedule Thursday's examination.

"Right now, it's a matter of Johan proceeding at his own pace," Mets general manager Sandy Alderson said on Tuesday. "He's going to have to be sensitive to how his body responds to increased workload. I wouldn't say it's something that we expected to happen, but I think in the overall course of things, it's probably not something that should be unexpected."

When healthy, Santana has given the Mets a strong return on their six-year, $137.5 million investment, producing a 40-25 record with a 2.85 ERA over his first three seasons in New York. But he has also displayed evidence of a deteriorating body; Santana underwent right knee surgery following the 2008 season and ended his 2009 season with a left elbow scope.

He remains under contract for at least the next two seasons, with a $25 million team option for 2014.

Meanwhile, first baseman Ike Davis is expected to return to New York this weekend for an examination that will determine whether or not he needs season-ending surgery. Davis has been on the disabled list since suffering a bone bruise in his left ankle during an infield collision in May.