Southampton have completed the signing of 26-year-old Scottish midfielder Stuart Armstrong, who joins the club from Celtic on a four-year deal.

With Dusan Tadic thought to be nearing a move to Dutch outfit Ajax, the St Mary's side have brought in a player whom they believe will have a huge impact on their fortunes next season.

A statement on the Saints' official website reads: "Southampton Football Club is delighted to announce the signing of highly-rated attacking midfielder Stuart Armstrong from Celtic.

"The 26-year-old has agreed a four-year contract with the club and will link up with his new teammates on Thursday for the start of pre-season."

Armstrong, who will report to the club's Staplewood training ground on Thursday, is looking forward to life as a Saint and insists he's committed to being the best player he can be every season.

"Every season, I put demands on myself to create and score goals," he told the club's website following the inking of his signature on Tuesday. "I hope going forward from here that it will be the same this term at St. Mary’s. 

"I’m looking forward to meeting everyone and I’m very excited to get started. It’s a four-year contract; there will be a lot to learn and I want to hit the ground running."