Manchester United's defeat of League Two side Cambridge United has set up a clash with Preston North End in the fifth round and Van Gaal's side are now best odds of 11/4 to lift the trophy.
Manchester United were expected to dispose of Cambridge United at the second time of asking and although the 3-0 win was routine enough, the bookies were sufficiently impressed to cut their price to 11/4 to clinch the coveted trophy, second only to Arsenal at 5/2.
Preston North End ( 200/1 ) were somewhat surprise victors over cup specialists Sheffield United on the same night and their reward is a home tie against the Manchester giants.
In the absence of Chelsea and Manchester City, Arsenal now find themselves favourites to win the competition for a second successive season and their public popularity has only increased since United’s victory. The Gunners will face a Middlesbrough side ( 66/1 ) who will be in high spirits following their 2-0 win over Manchester City in the last round.
Liverpool are also fancied to go far in this competition and are best odds of 6/1 with Coral to win the FA Cup. West Ham are up for grabs at 11/1 with the same bookmaker, despite some uncertainty regarding the eligibility of Diafra Sakho, the Senegalese striker scoring the winning goal against Bristol City in the fourth round.
It has been suggested that the Hammers may be ejected from the competition this season, however this looks to be an unlikely scenario and they will be facing West Brom at the Hawthorns in nine days time, confident that they can make it through to the semi-finals at least.
FA Cup outright best odds
11/4 Manchester United
11/1 West Ham
14/1 Stoke City
20/1 West Brom
25/1 Crystal palace
25/1 Aston Villa
33/1 Derby County