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BRADENTON, Fla. -- The Pirates made at least one offer of a six-year extension to promising young outfielder Starling Marte, which would have guaranteed him seven years in Pittsburgh, sources say.

According to people familiar with the situation, the Pirates earlier this spring agreed with Marte on a $512,600 2014 deal, which is $12,600 above the minimum and conforms to their formula for pre-arbitration players. But they've been trying to ensure he stays a lot of longer than that. The goal for the Pirates is to lock him up through at least two free-agent years, and a six-year extension on top of the one-year deal he already has in place would do just that.

The Pittsburgh Tribune-Review first reported that the Pirates had made Marte some multiyear offers, which they said he hadn't accepted.

While there's no word Marte will accept a deal, the sides could still be negotiating.

The Pirates have a history of locking up young outfielders to six-year deals. They gave Andrew McCutchen, the 2013 NL MVP, a $51.5 million, six-year deal two springs ago, and also gave Jose Tabata a $15.5 million, six-year deal. The deal for McCutchen was a great success while the one for Tabata hasn't quite worked out as well as expected; he's in the right-field mix, along with Travis Snider.

Marte, McCutchen and talented Gregory Polanco, who was sent to minor-league camp a little more than a week ago, are seen as the Pirates' gem of an outfield of the future. Marte, 25, emerged as a productive player last year when he hit .280 with 12 home runs and 41 stolen bases. He also had a .784 OPS and 83 runs, and he was a finalist for a Gold Glove award.