The duo shone in last weekend’s draw with Everton, producing a delightful move for Rooney’s second goal that evoked memories of Andy Cole and Dwight Yorke's combination in the Nou Camp in 1998.
Sir Alex is thrilled by what he’s seen from the pair, who have hit 45 goals between them this term, and is expecting further progress as they reach their peak in the coming years.
The Reds boss said: "Wayne is 26 now, Danny’s 21. You’d think that for the next few years they can only get better. And we hope so. With Danny being fit again and playing consistently, he’s developed better.
"Last week we saw something really special. I know there were a lot of references to Cole and Yorke and there were similarities, yes. I thought Welbeck’s movement was fantastic last week. Attacking-wise, we were terrific in the second half."
It remains to be seen whether both Rooney and Welbeck start Monday’s showdown with Manchester City, though Sir Alex has already stated United will attack at the Etihad.
One thing’s for sure: with the Reds having lost only twice on the road in the league this season and City still defending an unbeaten home record, something has to give.
"I think we’ll have to have a threat on Monday," Sir Alex added. "We expect our players to step up to the mark and offer a threat to City. No doubt about it.
"We have an interesting combination of things here: the team with the best home record in the country and then the team with the best away record in