Jose Mourinho said Alexis Sanchez would “complete our very young and talented group of attacking players” at Manchester United. Photo: @ManUtd via Twitter

LONDON – Ryan Giggs says Alexis Sanchez is a ready-made “superstar” who can give Manchester United a lift as they bid to chase down Premier League rivals Manchester City.

Sanchez on Monday sealed a move to United from Arsenal in a swap deal with Henrikh Mkhitaryan, saying he was “thrilled to be joining the biggest club in the world”.

The 29-year-old Chile striker, who came close to joining Manchester City last summer, has signed what is believed to be a four-and-a-half-year contract that will make him the highest-paid player in the Premier League.

It has been widely reported that Sanchez will earn a pre-tax salary of £500 000 a week at Old Trafford.

“Manchester United signing Alexis Sanchez is similar to Robin van Persie in the sense that they’re getting a ready-made superstar, and you’re seeing the contribution already with Anthony Martial upping his performances,” new Wales manager Giggs said on skysports.com

“That can happen when top players come in, those around them lift their levels, and there will be some difficult selection decisions for Jose Mourinho.

“However, Sanchez can also play on the right, as he did at Barcelona, so if Martial is flying then he may have to play in a different position, but those sorts of decisions are positive for a manager to have to make.”

United boss Mourinho said Sanchez would “complete our very young and talented group of attacking players” alongside the likes of Romelu Lukaku, Marcus Rashford, in-form Jesse Lingard and Martial, who has scored three goals in his past three Premier League games.

Giggs, United’s most decorated player, said it was an extra bonus that the former Arsenal man would be able to play in the Champions League – United play Sevilla in the first leg of their last-16 tie on February 21.

“To have somebody like that, who won’t be fazed by playing in the big games, makes the squad look really strong,” he wrote.

United, who have not won the Premier League title since 2013, are second in the table but trail Manchester City by 12 points – a gap that looks impossible to breach, even with four months of the season to run.

Sanchez took a parting shot in an Instagram post at ex-Arsenal players who have criticised his attitude.

Quiero agradecer al Staff Técnico, al equipo médico, a todos los compañeros con los que compartí muchas cosas lindas para el club y en especial a todas esas personas que no se ven en las portadas, pero que sin ellos nada seria posible, que son los que te preparan la comida y te cuidan día día, los que nos mantienen los zapatos limpios y campos de fútbol en las mejores condiciones para entrenar. Mil gracias a Ustedes por ayudarnos a mejorar cada día. Gracias por tanto cariño 😢. Hay personas (ex jugadores del club) que han hablado sin conocimiento de lo que ocurre en la interna y causan daño. Debo decir que siempre me entregué al 100%, hasta el último día, en que le pedí al Mister estar con el equipo, por que quería ser un aporte. Recuerdo hoy, una conversación que tuve con Henry, un histórico de Arsenal, que cambió de club, por la misma razón que hoy me toca a mi. Gracias por todo Gunners ! I want to say thanks to the Technical Staff, to the medical team and all teammates with whom I shared many nice things for the club and especially those people who do not see themselves on the covers, but without them nothing would be possible, which are there to prepare food for us and take care of us day by day, those who keep our shoes clean and the grass in the best conditions. Many thanks to you for helping us to improve every day. Thank you very much 😢. There are people (former club players) who have spoken with no knowledge of what happens inside the club and cause damage. I must say I always gave 100%, until the last day, when I asked to the Mister to be in the team, because I wanted to be a contribution. I remember today, a conversation I had with Henry, a historic Arsenal player, who changed club for the same reason and today is my turn. Thanks for everything Gunners! All we achieved and the good moments that I gave to the club, I want to dedicate it to the fans, they are the most important. Thanks for every time you sing Alexis Sanchez Baby

A post shared by Alexis Sanchez (@alexis_officia1) on

“There are people (former club players) who have spoken with no knowledge of what happens inside the club and cause damage,” Sanchez wrote.

“I must say I always gave 100%, until the last day, when I asked to the Mister (Arsenal manager Arsene Wenger) to be in the team, because I wanted to be a contribution.”

Armenia international winger Mkhitaryan, also 29, fell out of favour with United manager Mourinho after just 18 months at Old Trafford.

The Sanchez-Mkhitaryan deal is the latest move of a busy January transfer window during which Liverpool sold Philippe Coutinho to Barcelona for €160 million and signed central defender Virgil van Dijk from Southampton for £75 million.

Reports in Germany say striker Pierre-Emerick Aubameyang could be on his way to Arsenal from Borussia Dortmund.