I expect him to start on Sunday. I think it's the right move by Pellegrini. His pace, physicality and strength is ideal to play against Costa. Imagine Costa trying to bully Vinny and Mangala? No chance.
I'm not being dramatic, flapping, or knee jerking, but I think the game on Sunday might well decide the title. If they win they go 8 points clear, and I can't see a Mourinho side letting that slip. If we win it puts up two points behind them after a much trickier start which could give us the momentum.
When Van Persie scored that free kick against us in the 2012/13 season I thought it was pivotal, and so it proved, Sunday has a similar feel about it. Fingers crossed, Mangala could be the difference maker for us.