Yesterday McClaren, now in charge of Middlesbrough, was delighted to offer Benitez's Liverpool a tutorial in the art of winning but, once again, the catalyst for a victory which could prove highly significant when European places are allotted next spring was Stewart Downing.
He may have missed out on an England senior call-up last week but Benitez regarded the left winger as sufficiently dangerous to double-mark him, effectively, by fielding both Josemi and Steve Finnan, two natural full-backs, down Liverpool's right.
Finnan, so often a reserve under Benitez, marked Downing out of Boro's recent Carling Cup defeat at Anfield and once again he seemed to have his measure, initially forcing him persistently infield. Indeed 30 minutes elapsed before Downing was able to embark on one of his hallmark attacking raids and that ended in a cul-de-sac.
Yet, ominously for the visitors, he was gradually starting to find his range and, tellingly, when the young Teessider delivered his first two crosses of the afternoon Jimmy Floyd Hasselbaink and George Boateng might have scored a goal apiece.
Until then McClaren's side made most progress down the right where Ray Parlour looked a strong early candidate for man of the match. Normally Parlour would have found himself in direct confrontation with Harry Kewell but injuries dictated that Liverpool's left winger - recently put on a personalised fitness enhancing and weight-reducing regime involving partial separation from his team-mates - served as an ersatz striker alongside the similarly out-of-position Luis Garcia.
Neither impressed but both could plead mitigating factors. Without their input from the wings, Liverpool lacked width and crosses and, considering strikers as lauded as Hasselbaink and Mark Viduka were rendered near anonymous by Downing's early containment, Kewell and Garcia could scarcely be expected to fare better.
Although Garica did direct a right foot shot beyond the hitherto unruffled Mark Schwarzer just before half-time, it was rightly ruled out for offside and, by then, Liverpool had newly fallen behind.
If the sight of Chris Riggott extending his right boot to claim a rare goal was slightly startling, no such surprise surrounded the identity of its creator, Downing crossing the ball to the central defender.
The newly-fit Steven Gerrard replaced Dietmar Hamann early in the second half but, by now, Downing, having thoroughly confounded his early captors, was irrepressible. After intercepting a loose ball, his run and cross to Hasselbaink duly preceded Boro's second goal. All that remained was for Hasselbaink to slip a short pass forward for Bolo Zenden - increasingly influential in central midfield from where his passing ability hurt Liverpool - to dispatch a low shot past Chris Kirkland.