Last summer’s record signing bagged an 11-minute hat-trick – Ashley Fletcher also scored his first during the same devastating period – as Boro blew Hartlepool away with some clinical finishing.

The goals will have been a huge confidence boost for both players ahead of the start of the new season as a largely youthful Boro side played with great enthusiasm and quality to ensure the final pre-season friendly was won in style.

Lewis Wing had forged an early opening as Boro’s intentions were signalled early on, Marcus Tavernier shooting straight at Scott Loach, and Harry Chapman also found himself with space to shoot but lifted an effort over the top.

Wing went close before the half-hour when a Chapman cross was only half-cleared and the former Shildon youngster lashed a shot inches over Loach’s bar.

The opener came on 34 minutes, though, with Assombalonga showing his predatory instinct to convert from close range. Wing had rattled the bar before Chapman followed up with a strike which Loach could only parry, and Assombalonga was on hand to make it third time lucky for Boro with a cool conversion.

Two minutes later Assombalonga scored his second of the game. Chapman was the provider with a driving run, and when he looked to pull back and he had both Fletcher and Assombalonga waiting to apply the finish. He opted for the latter who duly made no mistake to double Boro’s lead.

It was 3-0 before half-time, and Fletcher was the man to profit from a great ball forward from Wing, allowing him to run on, round Loach, and tuck the ball home. And it would have been four – with a second for Fletcher after a ball in from Assombalonga- but a fortuitous deflection saved Pools.

That proved a short reprieve, though, and Assombalonga had his hat-trick before half-time when he powered home a Tavernier corner to make it 4-0.

It took a little over a minute of the second half to make it five, and it was Fletcher who scored his second of the game after Chapman was again the provider.

Assombalonga’s afternoon came to an end before the hour mark when he was immediately substituted after taking a bang on the knee, and that saw the arrival of Julien de Sart.

Hartlepool did fashion a couple of half-chances as the game wore on, but Boro were never seriously troubled and were able to end the game with more young players – Djed Spence, Stephen Walker, and Ben Liddle – getting some valuable minutes.

Hartlepool: Loach, Kioso, Kitching, Magnay, Noble, Donaldson, Muir, Hawkes, Davies, Newton, James. Subs: Catterick, Laing, Hawkins, Cassidy, Woods, Featherstone, Anderson, Richardson, McLaughlin, Dinanga.

Boro: Konstantopoulos (Ripley 60), Mahmutovic, Wood (Spence 60), Fry, McGinley, Wing (Liddle 77) Leadbitter, Tavernier, Fletcher, Chapman (Walker 77), Assombalonga (de Sart 56). 

Ref: A Miller

Att: 1747 (544 Boro)