The Scottish manager sacked the caretaker regime of Dave Bassett and Howard Wilkinson in the morning and then revamped his side to face the lowly Railwaymen.
Keith Gillespie got his first start of the season, Dion Dublin and Scot Gemmill were dropped to the bench, but it was David Connolly, another of the Foxes under-achievers this term, who caused most problems for Crewe.
The former West Ham man twice wrapped Clayton Ince's post in the first half, the second from a stunning free-kick.
Leicester were close to taking all three points then, having twice let Crewe back into the game.
Trinidadian keeper Ince was recalled to the Crewe side because of an injury to first choice Ben Williams and he saved the day early on, making two good blocks from Connolly, although he could do nothing with Lilian Nalis' stunning 20-yard volley on the stroke of half-time.
Crewe had suffered a setback on the half-hour when centre-half Steve Foster was knocked out in a collision with his own keeper Connolly.
But they rallied three minutes into the second half when Liverpool loan man Jon Otsemobor charged down the right and crossed for Mark Rivers to hook the ball home from close range.
But the home joy was short-lived, and seven minutes later Johannes Gudjonsson gathered Connolly's pass on the right side of the box and shot between Ince's legs for Leicester's second.
Dean Ashton came close to drawing Crewe level again when he bulleted a header from David Vaughan's corner only to see Peter Canero boot the ball off the line.
But Otsemobor was playing superbly, and when he fired a shot towards goal 25 yards out on the hour, veteran keeper Kevin Pressman failed to hold on to the ball and it carried over the line.