JUPITER, Fla. - Mets second baseman Daniel Murphy played half an inning Thursday before right hamstring tightness forced him from a 7-2 split-squad win over the Cardinals.

Manager Terry Collins said Murphy felt tightness when he rounded first base on a hit and again when he tagged up to score from third. Murphy did not take the field in the bottom of the first.

"It's a hamstring," Collins said. "That's why we sent him back right away to have it looked at by the guys in St. Lucie. So we'll see how he is tomorrow.''

In seven Grapefruit League games, Murphy is hitting .188 (3-for-16) with no extra-base hits.

Said Collins: "He's in a pretty good spot where we've got enough time to give him a couple of days [off] if that's what's needed.''

If Murphy misses time, Collins said utilityman Daniel Muno could see some action at second base.

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Jonathon Niese allowed one run and three hits in four innings. He struck out six.

Back in the swing

Dillon Gee tossed 32/3 scoreless innings in a 3-1 split-squad win over the Astros in Port St. Lucie. In his first outing since rejoining the starting rotation, Gee allowed two hits, walked two and lowered his exhibition ERA to 3.38.

Rafael Montero allowed one run in 32/3 innings, a lengthy outing considering he is being considered primarily for the bullpen.

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"We have to protect ourselves in case something else happens and we have another starter that we can rely on," Collins said.

Parnell's return

Reliever Bobby Parnell's long-awaited return could come on Friday in a minor-league game, Collins said. Parnell underwent Tommy John surgery last April.

Collins said reliever Zach Thornton has opened eyes in camp. He threw a scoreless inning against the Cardinals to lower his ERA to 1.80 in five appearances . . . The Mets optioned righthander Akeel Morris to minor-league camp . . . Josh Edgin returned to Florida two days after undergoing Tommy John surgery. The reliever was greeted by teammates as he walked through the clubhouse with his left arm in a sling.