United end a run of 11 hours without a first-half goal at home as a youthful side avenge the Boxing Day defeat with a stylish victory over Stoke through goals from Lingard, Martial and Rooney in a rare night of relaxation for Van Gaal.
The Reds fantastic crop of youngsters are flourishing under the Dutchman's tutelage and impress again at champions Chelsea on the 7th.
Lingard's brilliantly taken goal- set up by teenager Cameron Borthwick-Jackson- puts a vibrant and energetic United side ahead but the valuable lead is lost as Diego Costa scores in stoppage time to earn Guus Hiddink's side a share of the spoils.
The young players are keeping United in the hunt but suffer a setback after struggling Sunderland score early and late to boost their own hopes as Martial's goal is not enough to prevent a seventh league loss of the season.
To compound a bad Valentine's weekend for the team, Rooney is injured and will miss up to eight weeks as De Gea's own goal six minutes from time leaves United six points adrift of the top four.
Things go from bad to worse as the pressure again ratchets up on Van Gaal after the part-time minnows of Midtjylland sink woeful United in Denmark in the first leg of the Europa Cup last 16.
Memphis puts us ahead and we should push on from there but individual errors cost us dear as the Danes inflict another painful reverse on Van Gaal's frugal and fragile side.
In the Dutchman's defence, the Reds are bereft of 15 first-teamers but still win with ease at Shrewsbury to seal a Cup quarter-final as Smalling, Lingard and Mata score after substitute Will Keane is added to United's lengthy injury list.
Ahead of the second leg against Midtjylland, Martial is injured in the warm-up as 18-year-old Marcus Rashford starts and then scores twice on debut to become United's youngest ever European scorer.
It's just a flash in the pan, let's see how he does against anyone good, they said... we do.
Three days later, the Manchester-born youngster follows up his senior bow with a brilliant brace on debut as a United side with an average age of 25 stun title-chasing Arsenal at a jubilant Old Trafford to breathe new life into the campaign in one of the high points of our season.