The Broadway Stadium is turning into somewhat of a 'duck' ground for United, in our three visits in the past two years United have failed in all attempts to pick up maximum points and have scored just once. They had come into this fixture seven matches unbeaten and were looking to equal a club record of seven straight matches without conceding - that of course has gone out of the window.
Lopez had only recently been recalled from a loan spell at League Two side Barnet due to slim selection availability in attack due to injuries, and it turned out to be a shrewd move by the Boro after his treble put the home side into a three goal lead.
He had began his career with Athletico Madrid and had played in the same development side as Chelsea (flop) and Spain forward Fernando Torres - scoring in the 41st, 50th and 64th minutes of the game as his strikes won Boro's only second game in ten matches.
Boro's opener and Lopez's first of the afternoon came shortly before the break after both sides had threatened each others goal; he turned centre-half Neill Collins inside the box before firing past keeper George Long - he then tried another but from 20 yards Long tipped over.
Gavin Mahon, the former Queens Park Rangers and Watford midfielder was the power house for Boro and playing a good game, he was at the art of the second goal which came shortly after half-time and after Kitson had seen his header saved by Arnold; Mahon played a neat pass through the defence for Lopez to capitalize and finish.
There was action at the other end too, but United were thwarted, substitute Callum McFadzean went close with a head, as did Harry Maguire but it clearly wasn't to be the Blades day when Lopez - against the run of play fired home from the edge of the penalty area for his finale. Four minutes the nails were truly hammered in when Lucas Atkins made it four with his run and shot.
Whilst United had faltered at the back they did make up for it at the other end but excellent keeping from Arnold, rather than poor strikes from the forwards proved the difference in keeping a clean sheet. Perhaps the visitors wouldn't have scored enough to drew the game had there 'good' opportunities sneaked in the goal, but would have made a high scoring and more entertaining game for the couple of thousand traveling supporters who despite at 4-0 were still in good spirit and enjoyable chanting.