A flurry of first-half goals condemned MK Dons Under-23s to their first defeat of 2018 as Southend United ran out 5-0 winners on Tuesday afternoon.
Former Jamaican international Theo Robinson found the net four times in the first-half and put Southend United Under-23s on course to victory.
Josh Wright, who featured against MK Dons earlier this season, also put his name on the scoresheet during an impressive opening 45-minutes from the hosts.
Robinson was joined alongside first-teamers Wright and Jermaine McGlashan for United - while Rubio's side was predominantly made up of Under-18s.
Ben Tilney captained the youthful Dons XI, while, Sam Nombe also featured having scored two goals for Oxford City on the weekend.
From the opening whistle, the hosts took control of the tie and just 10-minutes into the game, they took the lead. Cotton worked his way into the box and took aim, Alfie Jones was there to deny the winger, however, the rebound fell into the path of Robinson who converted from close range.
The Dons pushed for an immediate reply through Sam Nombe. The striker was found in space by Jenson Wright - he could only drag his shot wide of the post.
Soon after, Jay Bird pounced on a loose pass in the Southend defence, with the forward quickly under pressure, he fired over the crossbar.
The missed chances proved costly as on 20-minutes, Robinson found the net for the second time. Having picked up the ball on the edge of the box, the 29-year-old played a clever one-two with McGlashan before finishing underneath Jones.
From there, Southend took the match, as they scored their third of the game just a minute later. Wabo found himself with his back to goal, his clever back-heel fell into the path of Josh Wright who converted from close range.
It took just 28-minutes for Robinson to complete his hat-trick, as the former Derby forward powered his way through the Dons defence before finding the far corner 6-yards from goal.
To their credit, the youthful Dons side continued to push Southend. Liam Sole jinxed pass a handful of Southend defenders only to see his goalbound strike deflect wide.
Three minutes from the break, Southend put the game to bed as Robinson scored his fourth of the game and United's fifth. He once again combined well with Wabo, before calmly finding the back of the net.
In truth, the second-half lacked the chances of the first 45-minutes. An hour into the game, Bird saw his shot cannon off the post, while five minutes later Tilney's free-kick grazed the crossbar.
The game will act as a good learning curve for Rubio's young side who continued to play for pride and remained professional throughout the whole 90-minutes.