Crystal Palace have signed Patrick van Aanholt from fellow Premier League strugglers Sunderland, the south London club announced Monday.

The 26-year-old Dutch left-back has arrived at Selhurst Park on a four-and-a-half-year contract for an undisclosed fee, although British media reports said he could end up costing the Eagles as much as £14 million ($17.5 million, 16.4 million euros).

Palace manager Sam Allardyce knows Van Aanholt from their time together at Sunderland and, according to the former England manager, was "instrumental" in helping preserve the northeast club's top-flight status last season.

Van Aanholt is Palace's second transfer window arrival following the £12 million signing of Jeffrey Schlupp.

Palace are just a point above bottom-of-the-table Sunderland in the standings and Netherlands international Van Aanholt is set to go into the Eagles' squad for Tuesday's league match away to Bournemouth.

"He (Van Aanholt) is a player that brings something to the team we have not got and hopefully he has an instant impact," Allardyce said.

"We had great success together at Sunderland where he was instrumental in keeping them in the Premier League last season," added Allardyce, whose side were beaten 3-0 at home to Manchester City in the fourth round of the FA Cup on Saturday.

"He will add pace and energy to our team, has strong defensive qualities and has the added ability to score and create goals. He will help in both departments."