Ryan Giggs has warned Manchester United's Carling Cup rookies they must show greater backbone if they are to succeed at Old Trafford. Holders United surrendered their place in the competition with a 4-0 quarter-final drubbing by West Ham, their worst defeat for nine years and their first loss of the season. A young side containing players such as Bebe, Chris Smalling and Javier Hernandez was swept aside as the Hammers defied arctic conditions at Upton Park to produce a sizzling display. Home fans stayed behind to take photos of the scoreboard and even though it was a callow United side, Sir Alex Ferguson will have found the experience hard to accept. Giggs, one of the few senior players in action, concedes that United wilted after West Ham's 22nd minute opener and again in the second half. The Welsh winger believes they had the fight knocked out of them far too easily. "Maybe heads can drop and the first goal came at a good time for West Ham," said Giggs. "Obviously we started the second half really well, but they scored from their first attack and maybe heads dropped. "But you are at Manchester United and you need to rise above that. "You still need to carry on playing your football and not let your heads drop." What do you think? Have your say.