(REUTERS) - Few Manchester United fans thought life after Alex Ferguson at Old Trafford would be easy but fewer would have imagined the possibility of a second successive season without any silverware and devoid of Champions League football.

Monday's 2-1 home defeat by Arsenal, which eliminated United from the FA Cup, means the Red Devils face the longest trophy-less run since the early days of Ferguson's silverware-laden era.

Ferguson, who succeeded Ron Atkinson in 1986 after the latter lifted the FA Cup in 1985, barely kept his job during his first four barren years in charge but ended the drought by winning the competition in 1990.

His successor David Moyes lasted less than a season and was sacked last year when it became clear United would miss out on any European competition.

Heavy spending by new manager Louis van Gaal has resulted in little improvement as United continued to look a side vulnerable at the back, bereft of ideas in midfield and lacking firepower up front.

Although in no immediate danger of following in Moyes' footsteps through the exit door, van Gaal must be revisiting some of his transfer decisions although he put on a brave face in the wake of his reject Danny Welbeck putting his former club to the sword.

"It was a surprise that Wenger put him in the lineup in that position," van Gaal said after Welbeck struck an opportunist second-half winner.

"Also, a lot of times against the club who a player was playing for, he shall be very motivated. But I think we gave that goal particularly."

Former United midfielder Roy Keane is confident van Gaal would be given time to pick up the pieces. "They've got to give him a chance. He needs two or three years to rebuild the club," he said.