The City boss has a number of options in midfield depending on the approach he wants to adopt. Barton and Bosvelt could be used to mix-it-up in centre midfield with SWP and Macca out wide.
However, Reyna has staked his claim for a start after a goalscoring performance last week, as have Tiatto and Sibierski who impressed off the bench.
Keegan is likely to stick with two up front to keep Chelsea's backline on their toes with Fowler possibly making way for Wanchope. Kevin Ellegaard will be on the bench after a minor injury to Nicky Weaver.
"Chelsea are as big a challenge as they come at the moment," said the City supremo.
"But there's no doubt about it - we can turn Chelsea over. We are one of the few teams who can go there with a realistic chance."
Last season City suffered a 5-0 defeat in London, with sub Jihai Sun getting his marching orders in injury time, but Keegan believes his side are better prepared this time round.
He added: "We got what we deserved last time, but I think we've got a much more balanced squad now with bigger personalities.
"It was the biggest defeat I've had here, and we've shored things up to make sure it doesn't happen again.
"But what we have got to remember is that if you are not quite there on the day teams like Chelsea will embarrass you."