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Mosquera, who arrives in north London for a reported £13m (€15m) transfer fee, has penned a five-year contract, which has an option for a further 12 months.

The 21 year-old is the Gunners' fifth signing of the summer, having already completed deals for Martin Zubimendi, Kepa Arrizabalaga, Christian Norgaard and Noni Madueke. 

Arsenal is also reportedly close to striking a deal for Sporting CP's Viktor Gyokeres, who is nearing a £63.5m (€72.9m) switch to the Premier League. 

Mosquera offers defensive versatility for Arteta and can operate at right-back or in central defence, with his arrival filling the gap in the squad left by Takehiro Tomiyasu's exit. 

The Spaniard completed more passes (1,822) than any other player for Valencia in LaLiga last season, while he also ranked third in the team for aerial duels won (32). 

Mosquera made 90 appearances for Valencia across all competitions since his debut in January 2022. 

He revealed earlier this month that a deal had already been agreed, telling Marca that a "new era" was beginning in his career, without specifically naming his new club.

That new chapter has taken him to Arsenal, a move that Arteta believes will strengthen the squad as it aims to end its 22-year wait for a Premier League title next season. 

"We're delighted to welcome Cristhian to Arsenal. As a 21-year-old defender, Cristhian has already performed consistently well with significant experience in La Liga," Arteta said.

"He is an intelligent player with good pace, who can play centrally and on both sides.

"He is a young player with exciting talent and enormous potential, who will fit well into our squad as we continue to prepare for next season.

"Cristhian adds good quality to our squad, and we look forward to working with him and making him feel at home with us.

"From all of us, we welcome Cristhian and his family to the club."