"It's an incredible feeling to be here," he said, according to Marca.

"Yesterday I was sad because I was happy in Sassuolo, but this was a great opportunity and I couldn't say no.

"I wanted to come to Barcelona, as soon as I heard of their interest I spoke to my agent. It's a dream and a great honour.

"This is a test and I know I haven't arrived as a starter, but I want to play well and stay for many years, that's my goal.

"At almost 32 years old, the role of a number nine is perfect for me.

"It's important to have a player like me in the team because I have other attributes."

Boateng, who started his career with Hertha Berlin, had a two-year spell with Spurs before joining Portsmouth in 2009.

After relegation from the Premier League and an FA Cup final defeat, in which Boateng had a penalty saved with the game against Chelsea goalless, he left for AC Milan.

Schalke, Las Palmas and Eintracht Frankfurt have also been home for the player, who signed for Sassuolo last summer.

But, after scoring four goals in 13 Serie A appearances, Boateng has moved to Spain and will count Lionel Messi among his team-mates.

"I'm a Barcelona player and the best player in the world, in any world, is Messi," said Boateng, who had previously been quoted as saying he preferred Real Madrid to Barca. "He's shown it over the past 10 years."

Barca are top of LaLiga, five points clear of closest challengers Atletico Madrid, while they are in the quarter-finals of the Copa del Rey and the last 16 of the Champions League.

Blaugrana coach Ernesto Valverde indicated the LaLiga leaders were unlikely to make any other major moves in the January transfer window, defender Jeison Murillo having already joined on loan from Valencia.

"I don't believe there will be any more arrivals. Although of course you can never be 100 per cent certain," Valverde said at a press conference.

Barcelona have also been linked with a move for Ajax midfielder Frenkie De Jong.

Valverde said: "That is a question for the player, not for me, and we will wait to see what he then says or decides. He will make up his own mind and all we can focus on are players who want to be at Barcelona."

Midfielder Denis Suarez has been linked with a move to Premier League club Arsenal.

Valverde continued: "We are happy with the squad, but there are always possibilities for departures for those who maybe do not feature as often.

"Those players could stay here and we would be happy or they could leave in search of more opportunities, we will evaluate all possibilities for them.

"We work internally and there is a lot of planning involved of which I am a part, but we will see how the market progresses."

The Barcelona boss added: "It is possible Denis will leave, but I don't know what will happen."

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