Fabio had a medical on Sunday and is likely to join the Bluebirds on a permanent deal, while Zaha is expected to join on a season loan.
Fabio joined United from Brazilian club Fluminense in July 2008, but unlike his brother Rafael has never established himself as a first-team regular at Old Trafford.
The 23-year-old was loaned out to QPR last season, and fell further out of favour at United this season when he picked up a rash red card during the FA Cup defeat to Swansea.
Fabio usually plays at left back and Solskjaer will hope he can strengthen a Cardiff defence that has conceded 38 goals this season, the second most in the league.
Zaha has made just four appearances for Manchester United since his £15m move from Crystal Palace and is yet to start a Premier League.
Last season however the winger was an influential creative player for Palace, scoring eight times in 50 appearances. He has also been capped twice by England.
The Old Trafford duo will join Solskajer’s three Norwegian signings, Magnus Wolff Eikrem, Mats Moller Daehli and Jo Inge Berget.
The new Cardiff manager could also add Stoke striker Kenwyne Jones to his squad before the window closes, with a swap deal with Peter Odemwingie looking increasingly likely.
Written by Steve Milne
