Andraz Sporar had earlier put Boro ahead in the second half as he met a low pass from Jones with a clever backheel flick across home goalkeeper Dan Grimshaw.

But the late winner was tough on Blackpool, who twice struck the post after the break through Gary Madine and Callum Connolly's glancing header.

Blackpool were further depleted by injuries and a positive Covid-19 test following their late Boxing Day defeat at Huddersfield, and Chris Wilder's in-form side duly bossed the first half.

Grimshaw saved from Onel Hernandez when one-on-one, Lee Peltier somehow directed an effort wide from just yards out as he ran on to Jones' drilled low cross, and Sporar was denied by a block.

Yet the Tangerines, who have lost five of their past six in the Championship, bounced back well and Sporar's opener came against the run of play.

Fry deflected Connolly's low drive inches wide of his own goal after the break, while Marvin Ekpiteta headed straight at Boro goalkeeper Joe Lumley from five yards as the hosts chased an equaliser.

Lavery looked to have earned a deserved point after Fry failed to deal with a long ball into the box - ending a run of four clean sheets - only for second-half substitute Watmore to stun the hosts.

Boro, unbeaten in six matches, remain fifth in the Championship but closed the gap to second-placed Fulham to six points, while Blackpool, who have just one win in their last 10, stay six points outside the play-off places in 13th.

Blackpool manager Neil Critchley told BBC Radio Lancashire:

"We don't deserve to feel like that after this game. The lads gave absolutely everything and we deserved that equaliser.

"We felt it was coming. They hadn't conceded in four games and very rarely look like conceding, but we caused them a lot of problems tonight and the game shouldn't end in that way."

Middlesbrough boss Chris Wilder told BBC Tees:

"I always knew this would be a really tough game for us. Blackpool were really aggressive, and asked questions of us defensively. That's what the Championship is all about.

"There are different hurdles to get over. We'd liked to have got over it in a better way, but the team showed a lot of different characteristics and qualities to get a big win.

"We got pushed back and you have to give credit to Blackpool for that. They're fighting for points and it would have been a big scalp for them to get a result off us.

"When you're in good form, picking up points and a big club in this division, you've got a target on your back and we have to deal with this."