PHILADELPHIA -- Eagles receiver Jeremy Maclin tore his right ACL during Saturday's practice and could miss the season.

Maclin went down at the end of a non-contact Saturday drill and appeared to be in pain while he was on the ground for several minutes. He was helped onto the cart and needed assistance getting off it and going into the team's practice facility.

Maclin thanked fans for their support on Twitter.

The oft-injured Maclin, entering the final season of his five-year rookie contract, has played an entire season just once in his career.

Several players tweeted messages of support to Maclin, including Eagles quarterback Michael Vick.

Robert Griffin III, the quarterback of the division rival Washington Redskins, also tweeted a get-well message.

After catching a career-high 10 touchdown passes in 2010, Maclin has combined for just 12 scores over his past two campaigns. He had an Eagles-leading 69 receptions for 857 yards and seven TDs last season.

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Jeremy Maclin's injury is not only a blow to him in a contract year, but also to the Eagles, who lose their best receiver for the season, writes Dan Graziano. Blog

Philadelphia is in its second full practice under new coach Chip Kelly. The first practice with pads is Sunday.

The Eagles signed wide receiver David Ball to the 90-man roster. The 29-year-old Ball played for Kelly at New Hampshire, and broke Jerry Rice's Division I-AA record for touchdown receptions. Ball spent time in training camp with Chicago and the New York Jets in 2007-08.

Two-time Pro Bowl wide receiver DeSean Jackson is Philadelphia's other starter. The team has veterans Jason Avant and Riley Cooper, along with several younger wideouts in camp.

Maclin has averaged 64 catches, 863 yards and six TDs in his first four seasons. His best year was in 2011 when he had 70 receptions for 964 yards and 10 TDs.

Information from The Associated Press was used in this report.