Afonso Alves scored twice to dash Manchester United's hopes of restoring a five-point gap at the top of the Premier League as they were held to a 2-2 draw at Middlesbrough.
The Brazilian's first goals for Boro capped a thrilling match at the Riverside and it was left to Wayne Rooney to grab an equaliser for the Red Devils when defeat was looming.
Earlier, Cristiano Ronaldo had struck his 37th goal of the season to open the scoring for United but Gareth Southgate's side were well worth the point at a snow-swept Riverside, and could even have stolen a late winner when Tuncay Sanli drew a good save from Edwin van der Sar.
The result sees United's lead over Chelsea down to three points - and they still have to go to Stamford Bridge.
United could point to several chances apart from their goals, but there was an unusual frailty in defence with Nemanja Vidic absent and Rio Ferdinand forced off with an injury.