The England international expects to keep his place after impressing in the 1-1 draw at Benfica.
"That's going to be a massive game. We knew it was going to be a big week but it's one we're all relishing," Smalling told manutd.com.
"[Some people are already writing Chelsea off] but I wouldn't say they're too old to win the league. They're definitely going to be up there or thereabouts. They've signed some good players and a lot of them will have fresh legs."