Manchester United manager Alex Ferguson reacts after arguing with Manchester City manager Roberto Mancini . REUTERS/Darren Staples
The Belgian defender rose unmarked just before halftime at the Etihad Stadium to settle a compelling and frantic derby that lacked quality but more than made up for that in tension.
United could not respond as City moved above their neighbours on goal difference with a match at Newcastle United and a home game with strugglers Queen Park Rangers to come.
Both sides have 83 points but the momentum is now with City who have clawed back an eight-point deficit since Easter to move within sight of their first English title since 1968.