David Moyes had apparently been keen on the Inter Milan midfielder, who is also a starter for Colombia, with Javier Hernandez rumoured to be heading in the other direction, but it seems that Chelsea are now in the lead for his signature.
Guarin would be a useful player at United, but perhaps not a great one - he's something of an all-rounder, offering a bit of everything. United could really use that, and it's increasingly rare in players now, but by the same token, Guarin isn't quite of the class of other targets like Ilkay Gundogan that we've been linked to.
Nonetheless, there's no doubt it'd vastly improve our options in both team and squad for the rest of the season, and £15m and reasonable wages mean there'd be plenty of room to get in other players too. It'd be a pretty good option if Chelsea don't get there first.