Manchester United have extended Ecuadorian defender Antonio Valencia's contract by a year, the Premier League club said on Tuesday. United said on their website (www.manutd.com) that a clause had been triggered to keep the 31-year-old international at Old Trafford until at least June, 2018. The wing-back has made 271 appearances for United and scored 21 goals, winning six trophies, since joining from Wigan Athletic in 2009. Valencia has started 23 matches in all competitions this season under manager Jose Mourinho and was voted United's Player of the Month by fans in November.