Rodgers confident in Sterling

Borussia Dortmund chief executive Hans-Joachim Watzke insists Borussia Dortmund would happily welcome back Manchester United midfielder Shinji Kagawa one day.

Watzke's claims come after the Japan international revealed to a local TV station that he was disappointed with his debut season in England, and would be open to a return to Dortmund in the future.

The attacking midfielder was frustrated by injuries and a lack of regular first-team football in his debut campaign in the Premier League, leading to speculation he is unsettled and a return to the Bundesliga could be on the cards.

"Shinji (Kagawa) is a player we would welcome back," Watzke told BILD. "The door is always for him at our club."

But Watzke knows that the chances of the 24-year-old making a sensational return are unlikely after just one season in the Premier League.

Boss David Moyes has spoken of his excitement at the opportunity of working with the gifted Kagawa, and former Dortmund midfielder Thomas Kroth admitted the new United boss is unlikely to part with his promising midfielder.

"I believe Shinji Kagawa will be staying on at Manchester United," Kroth added.

"But football is a fast business, you never know."

The forward, who had just three league substitute appearance to his name from the previous campaign, was handed a surprise start against Manchester City last August aged just 17.

He then started the next 15 matches in succession, during which time he also made his full England debut, and after signing his first major contract he remained a key part of Rodgers' first-team plans until injury saw his season ended in late March.

But the manager believes a summer of recuperation has been beneficial and expects even more from the player this time around.

He has already responded with goals in both of Liverpool's pre-season friendlies so far and Rodgers said: "I thought he was outstanding the other night (against an Indonesia XI).

"He's come back refreshed. He did work over the course of pre-season and was back and forward from his holidays into Melwood preparing himself well.

"He looks so fit, he looks sharp, he looks better than what he was last summer when I came in and I think he'll play a big part for us again this season.

"At 18 years of age, he has so much potential.

"If we nurture that well and he can retain his focus and mentality, he can be a big talent for Liverpool.

"I've been pleased with what I've seen from him so far."

Sterling, signed for an initial £600,000 from QPR aged just 15, was given his first-team debut by previous manager Kenny Dalglish in March 2012.

However, it was not until he was thrust into the limelight by Rodgers that he began to show true potential.

"It was a year ago when I came into the club and he came away with us on pre-season as a reserve/youth-team player, and his enthusiasm, quality and tenacity really hit me," Rodgers told liverpoolfc.com.

"He ended up starting the season after the West Brom game and for the first six months he was sensational.

"He ended up getting a full England cap, which shows you the impact he made at 17 years of age, and make over 30 (Liverpool) appearances.

"Towards the end of the season, there was a natural drop-off purely because of the youthfulness of him and also because of the pressure of playing for Liverpool and at the very top end of the game.

"I took him out of that, he had a little injury at the end of the season as well but I wanted to protect him and make sure he doesn't have too many miles on the clock too early."

While Sterling brings youthful enthusiasm to the squad a player with probably greater significance at the other end of his career and opposite end of the pitch.

Centre-back Kolo Toure was signed on a free after leaving Manchester City and the 32-year-old has already been pencilled in as the natural replacement for the now-retired Jamie Carragher in terms of leadership.

Carragher spent the second half of last season partnering Daniel Agger in the heart of the back four after Martin Skrtel was dropped.

There was much speculation about the Slovakia international's future and while there has been no hint of a move emerging so far the arrival of Toure may mean he is relegated to the bench once again.

Agger, who will most likely retain his place, has welcomed the addition of the Ivory Coast international's experience.

"He's been around so long, he knows what he is doing. He is a good guy, too," said the Denmark defender.

"I haven't played with him much yet but he's a class footballer. We've known that for a long time, so it's not a surprise.

"He is talking a lot on the pitch, he is well organised and he is physically on top. He is an all-round player. He's good.

"Experience is important for the team. We need it if we want to reach our goals."