Warnock was appointed as the club's new manager on an 18-month deal on Saturday morning after a meeting with owner Ken Bates in Monaco on Friday and, although temporary manager Neil Redfearn picked the side, the former QPR boss spoke to his players before kick-off and also at half-time.
His interval address may well have been as a result of a dismal first-half performance which saw Mamadou Bagayoko open the scoring, but whatever he said did not seem to have worked when the Malian made it two after the break.
That prompted an outpouring of dissent on the terraces, with Leeds' fans renewing their feud with Bates over a perceived lack of investment.
At two down, Warnock's plans to achieve the promotion target set by former manager Simon Grayson looked unlikely, something that remained despite Andros Townsend and Adam Clayton levelling matters.
But, Warnock's career has always been colourful and when Becchio cracked in a curling drive from 20 yards, it suggested that will continue to be the case.
The last time Warnock was at Elland Road, his QPR side were beaten 2-0 in December 2010, and his new team started little better than his last one fared.
Doncaster midfielder Brian Stock drove over from the edge of the box after the ball came loose and then, with 10 minutes on the clock, Habib Bamogo back-heeled El-Hadj Diouf's flick-on against the post.
That stirred Leeds briefly and Robert Snodgrass and Clayton fashioned a chance for Becchio, with his back header being tipped over by a scrambling David Button.
But with the quality so low, a goal was always likely to be as a result of a mistake and so it proved when Doncaster took a 32nd-minute lead.
James Hayter found himself through on Andy Lonergan's goal and, although the goalkeeper smothered his effort he did not hang on to the ball and Bagayoko, on for the injured Bamogo, tucked into the vacant goal.
Doncaster's fans, no friends of Warnock after his long stint in charge of their local rivals Sheffield United, quickly taunted him from their position next to the directors' box and his response was to make his impromptu half-time address, but the response was not immediate, with Doncaster the first to impress after the restart.
Leeds were caught short at the back and, after Giles Barnes threaded Hayter in, the striker was desperately unlucky to crunch the bar.
The close shave only put off what had been coming, though, and Bagayoko made it two with 54 minutes gone, tapping into an open goal for a second time after Diouf turned Tommy Spurr's cross into the six-yard box.
The goal triggered mass unrest amongst the home fans, with Bates at the centre of the ire, and even an immediate response from Townsend did little to pacify them.
A minute after Bagayoko's second, Becchio fumbled his way into the box, the ball fell to Townsend and he placed a crisp drive beyond Button.
The game was well and truly alive now, with Becchio bringing a low save out of Button after Snodgrass' cross and then the keeper saving at the feet of McCormack.
Leeds had now replaced Doncaster in the ascendancy and when they equalised with 10 minutes remaining, it had been coming. Snodgrass fizzed a cross in from the left and Clayton arrived in the box to stab it beyond Button on the volley.
That was not the end of the drama however and, after a lengthy delay after Robbie Rogers was knocked out, Becchio took in a loose ball and capped a memorable turnaround.