Saints manager Ronald Koeman believes new signing Fraser Forster will provide the club with an outstanding keeper for years to come – but he has challenged previous number one Artur Boruc to provide him with real competition.

England international Forster arrived in a £10m deal from Celtic at the weekend, and will go straight into the team for Sunday’s Premier League opener against Liverpool.

The 26-year-old replaces Boruc, 34, as the club’s first choice keeper, with the Polish stopper now unlikely to stay beyond next summer, when his contract expires.

But Koeman has asked Boruc to be professional and challenge Forster for his place in the side.

“Everybody knows the situation with Artur Boruc – it’s the last season of his contract – so this is a choice about the future,” the Saints manager told the club’s website.

“I’ve already spoken to Artur, and Fraser Forster comes in as the first goalkeeper. Artur has to give real competition, and I expect that, because that’s the professional way.

“It’s a difficult situation for him, I understand that, but it’s football. We need competition in all of the positions.”

As well as Forster and Boruc, Saints also have club captain Kelvin Davis, 37, and Paulo Gazzaniga, 22, as goalkeeping options.

Speaking about the arrival of Forster, Koeman added: “I’m very happy because he’s a very good goalkeeper.

“He’s England’s third goalkeeper, he has a lot of experience and he’s played at Champions League level.

“The squad is young but, like the other goalkeepers in Kelvin and Artur, he is experienced and we need that type of person in our squad.

“But goalkeepers normally have a longer career than outfield players, so this is about the future,” he continued.

“For the next three, four, five years, we have a very good goalkeeper.”