London, February 13(Reuters) - David de Gea's late own goal earned Sunderland a 2-1 win over Manchester United on Saturday and a vital three points in their bid for Premier League survival. Tunisian Wahbi Khazri gave the hosts the lead after three minutes when his wide free kick from 30 metres eluded everyone on its way to the far corner of the net. Anthony Martial grabbed the equaliser six minutes before halftime, the young French striker dinking the ball in from a tight angle after Sunderland keeper Vito Mannone had saved Juan Mata's firm shot. De Gea made fine saves to deny Dame N'Doye and Lamine Kone but the Spanish keeper failed to deal with Kone's powerful header eight minutes from time, deflecting the ball over the line to leave United six points behind fourth-placed Manchester City. "Today was very similar to the way the Manchester City game went but this time we got what we deserved from the chances we created," Sunderland manager Sam Allardyce told BT Sport, referring to his team's 1-0 defeat by Manuel Pellegrini's men. "I thought we might be punished for not taking them and wondered whether it was going to go our way but it ended up being an unbelievable win for us."