The Reds arrived at the Riverside Stadium having taken just one point from their past two matches and manager Jurgen Klopp chose to drop goalkeeper Loris Karius.

However, his replacement Simon Mignolet had little to do after Lallana headed home Nathaniel Clyne's cross before the break as Liverpool seized complete control.

Sadio Mane wasted several opportunities but Lallana was clinical, first crossing slickly for Divock Origi to prod home a fine team goal, then side-footing in a pass from the Belgium striker for the third.

The three-goal margin was enough to move Liverpool second, while Boro - competitive in the first half but abject after the break - drop to 17th.

The gulf in class between these two teams was clear. Often keeping possession with 10 home shirts behind the ball, Liverpool waited for key moments to inject pace into attacks with devastating effect.

Klopp's decision to replace Karius drew focus before kick-off, but that will switch to his side's qualities after this display.

Lallana was at the centre of everything they did well. Shortly after arriving at the back post to head home the opener, he slid in to block a stinging Adam Forshaw shot at the other end.

Mane struck the woodwork, giving the hosts hope in the second half, but a one-touch interchange involving the Senegal international, Georginio Wijnaldum, Lallana and Origi for the second goal epitomised all that was good about the classy visitors.

Lallana has now been involved in 12 goals this season, scoring six and making six - a healthy improvement on the 10 he was involved in across 30 appearances in 2015-16.

And at the other end Liverpool also answered questions. They have scored 40 goals in the league after 16 matches - the last time they did that they won the title in 1978-79 - but the fact they have still conceded one more goal than Boro is worrying.

Even without the composure Joel Matip often offers, his replacement Ragnar Klavan formed part of a solid defence alongside Dejan Lovren, with Mignolet only making one key save to deny Viktor Fischer before half-time.

Even against a Reds side who had conceded six goals in their past two matches, Boro could not overcome their growing tendency to be blunt in front of goal.

A three-goal margin suggests their problems were defensive, but with striker Alvaro Negredo constantly isolated, perhaps more support for him in the final third could have at least offered them a footing.

Their 13 goals and their tally of 41 shots on target are both league lows. They managed three on target on Wednesday but have not had four in a match this season.

Aitor Karanka's side are clearly committed - they have made more tackles than any side this season - but they are yet to win two games in a row since being promoted.

At this stage last season Newcastle had a point more than Boro but ended up being relegated.

Middlesbrough will have far easier nights, but they are edging close to trouble and solving their attacking difficulties could go a long way to aid their fortunes.

Middlesbrough boss Aitor Karanka: "We have to remember how good we've been in the games before this, against Bournemouth and Hull City. I think they were the best team we've faced this season.

"We tried, especially in the second half with two new players, to press higher. It proved impossible to stop them. I can admit they were much better than us."

Liverpool manager Jurgen Klopp: "We had moments in the first half where we were static and even I was confused. We did much better second half, we could have finished more often.

"Adam Lallana is improving even when he doesn't score, but it's nice he's in that situation. About a year ago I had sat him in the office and I was happy with him but he was like 'I'm not scoring' - and I said he wasn't in the right positions. Tonight he was twice in the right position and it was wonderful."

(BBC)