Ange Postecoglou says Celtic are still looking to bring in “two or three” players during the summer transfer window.

The Scottish Premiership champions have already made five additions headlined by the signing of impressive winger Jota on a five-year deal from Benfica for £6.5m following his successful loan spell last season and right-back Cameron Carter-Vickers in a four-year deal from Tottenham.

Lanus left-back Alexandro Bernabei has also joined in a move worth £3.75m along with Dundee United goalkeeper Ben Siegrist and forward Daizen Maeda from Yokohama.

But manager Postecoglou, who led Celtic to the title and League Cup in his first season in charge, is desperate for his side to improve and for the squad to strengthen.

“We’re still looking to bring in two or three players,” he told Sky Sports News in Austria during the club’s pre-season tour.

“There’s still a couple of areas where we need to strengthen up and we’ll do that. The challenge is to improve irrespective of what happened last year. If we didn’t win the title, we’d be looking to improve to try and win it.

Image: Ange Postecoglou led Celtic to the title and League Cup in his first season in charge,

“If we do improve then it gives us a chance to be successful. That’s what I’ve said to the players from day one this year. It’s not about repeating last year’s success, this is about being a better version of ourselves this season on all fronts.

“We strengthened during last season whereas this year we’re a lot more settled. It gives a chance to work on our game and get the players a better understanding of that.

“I don’t think there’s a manager who would come and say they’ve had a bad pre-season or their signings aren’t good. We all say the same stuff and it’s only when the season starts that you understand where you’re at.

“The lesson for us is we didn’t have a great pre-season last year and it didn’t stop us from being successful. You’ve got to seek continuous improvement whatever your starting point is.”

Jota helped fire Celtic to the Scottish Premiership title after joining on loan from Benfica

Image: Jota helped fire Celtic to the Scottish Premiership title after joining on loan from Benfica

Signing Jota and Carter-Vickers on permanent deals will come as a major boost for Celtic’s future and Postecoglou knows the importance of signing the pair.

“It’s not just about retaining them because they had good seasons last year, for me, if they were available this year I’d sign them anyway,” he said.

“They’re players who I know will improve and have their best years ahead of them. The added bonus is we already know what they’re like as people and they fit really well with the culture of the group we have. They’re two exciting players.”

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Celtic winger Jota signed a permanent deal after feeling at home at the club as he relishes the chance to experience ‘special’ Champions League nights.

Centre-back Christopher Jullien had looked like he was on his way out of the club but he is currently on Celtic’s pre-season tour.

Postecoglou explained: “Everyone’s future is the same, everyone’s future is unknown. None of us have any certainty about what we do.

“All we can do with Chris and the other lads while they’re training with us is I treat them as one of our players and if that changes in the future, it changes.

“The players have to make their own decisions about their futures as well, they know what they want to do and where they’ll get their best opportunities. They’re not discussions I have with the players unless they come and seek them with me.”

Image: Harry Kewell agreed to become a Celtic first-team coach in June

Harry Kewell has also started working with the squad in Austria after agreeing to become a first-team coach last month. The former Liverpool winger is part of Postecoglou’s plans to bring improvements this season.

“I’m always conscious of making sure every year we bring a freshness to everything we do particularly with the players,” he added.

“We had a successful season last year and we know we have to up a level this year. If players come in and see no change, I don’t think it sends the right message.

“Harry has had a crack at trying to be a manager and he wants to carve out a career for himself. He brings energy and enthusiasm for us.”

Celtic fixtures: Aberdeen test up first on Sky Sports

Celtic begin their Scottish Premiership title defence at home to Aberdeen, live on Sky Sports, with the first Old Firm clash not scheduled until September.

Ange Postecoglou’s champions kick off in front of the Sky cameras at 4.30pm on Sunday July 31.

Their first meeting with Rangers will be at Celtic Park on September 3, and Celtic start 2023 with a visit to Ibrox on January 2, before hosting their biggest rivals again on April 8 in their third-last game before the split.

Celtic’s final game before the month-long break for the World Cup is at home to Ross County on November 12, and they return to action with a trip to Aberdeen on December 17.

Christmas Eve brings a home game against St Johnstone, and Postecoglou’s side round off before the split with a trip to newly promoted Kilmarnock on April 15, before hosting Motherwell a week later on April 22.

Follow the summer transfer window with Sky Sports

Who will be on the move this summer before the transfer window closes at 11pm on September 1?

Keep up-to-date with all the latest transfer news and rumours in our dedicated Transfer Centre blog on Sky Sports’ digital platforms. You can also catch up with the ins, outs and analysis on Sky Sports News.