United manager Sir Alex Ferguson said: 'It was a disappointing performance but our character and attitude got us the points.
'I keep getting asked whether the Premiership is over and hope I go into the booby trap. We don't even think about it. It's irrelevant.'
The bookies were not sharing Fergie's reticence. Ladbrokes announced they were going to pay out on a United championship almost four months early - an offer they extended to include Fulham's First Division campaign following their 2-0 win at QPR.
Birmingham earned a Worthington Cup final date with Liverpool in Cardiff later this month with a 4-1 victory at St Andrew's, 4-2 on aggregate, over Ipswich.