Ruud van Nistelrooy's Manchester United roared to an entertaining 5-2 victory against Leicester to reach the Carabao Cup quarter-finals as the post-Erik ten Hag era began with a bang.The Red Devils called time on the Dutchman’s 29-month reign on Monday, leading to the club’s popular former striker stepping up from his role as assistant manager while a permanent head coach is recruited.United are in talks to hire highly-rated Sporting Lisbon boss Ruben Amorim and the club appear to be safe in hands should negotiations drag on judging by Wednesday’s win against Leicester.Van Nistelrooy – who returned to the club in the summer as one of Ten Hag’s assistants – celebrated as excitedly as those in the Old Trafford stands when Casemiro opened the scoring with a stunner 15 minutes into his first match in temporary charge.Alejandro Garnacho struck another before Bilal El Khannouss pulled one back for much-changed Leicester, only for United to hit back through a deflected Bruno Fernandes free-kick and Casemiro’s second of the night.Conor Coady cut the lead in first-half stoppage time, but Fernandes coolly scored his second on an evening when fan favourite Van Nistelrooy’s name frequently filled the air.United had won just one of their eight matches in all competitions since swatting aside Barnsley 7-0 in the previous round of the Carabao Cup and they looked hungry after what Van Nistelrooy called a "hectic" build-up.The caretaker boss made four alterations against Leicester, whose manager Steve Cooper made nine changes and saw his side fall behind to a fantastic 15th-minute opener.Fernandes smartly stepped over a Garnacho pass, giving Casemiro space to take a touch and unleash an outstanding strike from nearly 30 yards that