Rafa Benitez has revealed Newcastle United never expected Mikel Merino to stay at St James' Park for long.

A great enigma of recent times is why the Spaniard left Tyneside after just 25 appearances. Merino initially joined on loan in 2017 but, within three months, a clause was triggered that made the move permanent.

Benitez brought his compatriot - then a 20-year-old - to the Premier League and he impressed on arrival. However, a back injury disrupted his season and, when he returned, the more established Jonjo Shelvey and Isaac Hayden were preferred as Newcastle stormed to a 10th-placed finish in their first season since promotion.

Merino departed the following summer and Toon fans were left scratching their heads as to why the prodigy moved on so soon. Since his exit, the now 27-year-old has developed into a starter for Spain, with performances for Real Sociedad attracting interest from Manchester City and Liverpool.

He has a reported PS52million release clause but Benitez, reflecting on Merino's time at Newcastle, explained why Premier League clubs may find tempting him to England difficult. The former Toon boss told AS: "We convinced him (Merino) to come (with a low release clause). From the beginning, we knew that his time at Newcastle was going to be fleeting.

"The idea was that he would bring us quality and convince him to stay with us longer but, due to his quality and being Basque, he was a player that was impossible to retain."

Benitez also opened up about how he needed to become pragmatic once earning Premier League promotion. One of his signings, which turned out to be a flop, was Joselu, the now Real Madrid striker who recently clinched Champions League glory.

"The Premier League has a lot of rhythm and a lot of speed. Due to the conditions of our club, our team was the protagonist in the Championship, but in the Premier League, we had to play more on the counter-attack.

"The other forwards adapted better than Joselu to the Premier League. He helped us a lot in the aerial game and especially in the games in which we had the initiative. With the ball close to the area, he always showed his quality in controls, passes and shots."