SO much for Middlesbrough only being able to defend then. The Teessiders might have kept their seventh clean sheet of the season last night, successfully shutting out a Derby County side boasting England’s all-time record goalscorer, Wayne Rooney, but it was at the other end of the field where they sparkled as they recorded their biggest win of the season.

Boro scored three goals under Neil Warnock for the first time as they flexed their attacking muscles, with the manager’s tactical tweaks and bold team selection eliciting just the response he would have wanted.

The hosts were the better side throughout the first half, claiming a deserved lead through Britt Assombalonga’s close-range finish, and cut loose as the game opened up in the second period.

Matthew Clarke’s own goal doubled their lead, before Marvin Johnson capped an impressive cameo from the substitutes’ bench with an excellent curled finish into the corner. Having inherited a side that looked bereft of an attacking threat when he was appointed at the end of last season, Warnock has somehow fashioned a team that boast goalscoring options that would have seemed unfathomable last term.

Derby were dreadful – if Rooney is appointed as permanent manager in the next few weeks, he will have quite a job on his hands – but that should not detract from the quality of Boro’s attacking display as they rose to seventh in the table.

Having been disappointed with Saturday’s 1-0 defeat to Norwich, a result that ended a ten-match unbeaten run, Warnock’s side could hardly have been more impressive as they immediately got back to winning ways.

It was a positive night for everyone wearing red, but will have been especially enjoyable for Duncan Watmore, who was making his Middlesbrough debut just over a week after he was handed a short-term deal until mid-January. Prior to last night, Watmore’s most recent senior start had come on Boxing Day, when he lined up for Sunderland in League One in a goalless draw with Bolton Wanderers, but his move down the A19 has provided him with a somewhat unexpected opportunity to resurrect his career.

This was a decent start to his time in a Middlesbrough shirt, with his energetic running down the left-hand side forcing Derby full-back Nathan Byrne onto the back foot. Watmore’s best moment came when he set up Assombalonga’s opener with a deft header, but Neil Warnock will have been just as pleased with the 26-year-old’s general fitness and wellbeing given his wretched luck with injuries over the last few seasons.

Watmore was joined in last night’s starting line-up by Patrick Roberts, another attacking talent who is seeking to get his career back on track after a difficult 12 months. Roberts’ loan spell on Teesside in the second half of last season didn’t really go to plan, with a hamstring problem severely limiting his game time, but Neil Warnock clearly sees something in the 23-year-old, even if last night’s appearance in the starting line-up was only his third since his return from Manchester City.

Roberts is not a youngster any more, so if he is ever going to make it into the first-team set-up at the Etihad, indeed if he is ever going to make it anywhere in the Premier League, it is surely time for him to start standing out at Championship level. Last night’s display was a start, with his dribbling ability taking him into the Derby penalty area on a couple of occasions. He will hope to be able to build on it with a sustained run in the starting line-up in the next few weeks.

With Watmore, Roberts and Marcus Tavernier in the line-up last night, Warnock abandoned his wing-back formation and went for a flat back four and a 4-2-3-1 system that was presumably conjured up in an attempt to enhance Boro’s attacking threat.

The switch did not make the hosts any less secure defensively, and while Derby’s midfielders tried their best to close down their opponents, Boro’s creative players gradually came to the fore.

The Teessiders might have opened the scoring after just five minutes were it not for the reflexes of Derby goalkeeper David Marshall, who got down well to turn Assombalonga’s low strike around the post.

Marshall was Scotland’s hero earlier this month as his penalty-saving heroics helped secure a place at next summer’s European Championship finals, but he was unable to prevent Assombalonga breaking the deadlock when he threatened again shortly after the half-hour mark.

Jonny Howson’s cross from the left flicked off the head of Andre Wisdom, enabling Watmore to intelligently head the ball back across the area. Assombalonga reacted quicker than Derby defender Matthew Clarke, and after muscling ahead of his opponent, he was able to bundle home from close to the goalline.

It was Assombalonga’s second goal of the season, and a third almost arrived five minutes later. The Derby defence failed to clear Roberts’ free-kick from the left, but after swooping on the loose ball in the 18-yard box, Assombalonga dragged a low shot just wide of the right-hand post.

Derby’s first-half attacking was fitful at best, with Wayne Rooney’s attempts to pull the strings from his new defensive-midfield role amounting to very little.

Rooney saw an 11th-minute shot blocked by a well-positioned Dael Fry, and while Marcus Bettinelli was called into action a few moments later as he claimed a low strike from Tom Lawrence, the Rams looked like a side that went into last night’s game having failed to score in more than three-and-a-half hours of football.

Their poor first-half showing resulted in former Sunderland striker Martyn Waghorn being hauled off at half-time, and his replacement, Louie Sibley, almost made an immediate impact as he was presented with Derby’s best chance of the night 45 seconds after the restart.

Sibley found himself in space on the left of the penalty area, but his low strike flashed past the right-hand post when a more clinical finish might well have caused Marcus Bettinelli problems.

That was as good as things got from a Derby perspective, with the introduction of Djed Spence and Marvin Johnson from the substitutes’ bench midway through the second half injecting some renewed energy and vigour into Boro’s display.

Spence set up two chances in the space of a minute with his runs down the right, picking out George Saville on each occasion. The Northern Irishman side-footed his first effort over the crossbar from the edge of the area, before his second was thwarted by a fine save from Marshall.

Johnson was similarly purposeful on the opposite flank, and his 71st-minute cross held the key to Boro’s second goal. His low delivery caused panic in the Derby defence, and while Clarke was able to get to the ball marginally ahead of Assombalonga, he only succeeded in prodding it into his own net.

With Derby’s defence tiring, Boro’s replacements had the run of the final third in the closing stages, and Johnson added a third goal with seven minutes left.

The substitute galloped clear down the right-hand side, before stepping inside adeptly to curl an excellent finish into the left-hand corner.