LONDON, Aug 21 (Reuters) - Chelsea have completed the signing of Dutch international defender Khalid Boulahrouz from Hamburg SV, the London club said on Monday.
The 24-year-old passed a medical and agreed personal terms at Stamford Bridge over the weekend and watched Chelsea begin the defence of their Premier League title with a 3-0 win over Manchester City.
He has signed for an undisclosed fee.
Boulahrouz made his international debut against Liechtenstein in September 2004, played seven of the Netherlands' World Cup qualifying games and started in their last two games in the tournament.
Despite measuring only 5ft 9ins he is a solid centre back but can also play fullback on either flank, a versatility that made him an appealing option for Chelsea coach Jose Mourinho.
'In a short squad and in a country where you can have only 16 players for a match, it's important to have cover for many positions,' Mourinho said.
His arrival further dampens the chances of England fullback Ashley Cole moving to Chelsea from Arsenal but open the door for Frenchman William Gallas to leave.
Peter Kenyon insists Chelsea's transfer policy is to buy young players - despite the summer arrivals of Andriy Shevchenko and Michael Ballack.
Shevchenko and Ballack, both 29, were available in their prime and too good to ignore, according to Chelsea's chief executive.
The Blues have also bought Salomon Kalou, 21, Mikel John Obi, 19, and latest signing Khalid Boulahrouz, who is 24.
Kenyon said: 'Our overall philosophy has not changed. We were able to take two unbelievable opportunities this summer in terms of Shevchenko and Ballack.
'They will add great experience to what's becoming a fantastic squad. That's been balanced by Kalou, Mikel and Boulahrouz.'
He will wear the number nine shirt at Chelsea and is available for tomorrow's Premiership game at Middlesbrough.
Kenyon said: 'This is one that's happened under the radar and quickly. We've been looking at various options. This one came up and we decided to move. We were able to conclude it quickly.
'He has got a great reputation and will fit well in to the Chelsea team and Premiership football.
'His qualities speak for themselves. He will be a very good addition and I'm looking forward to seeing him soon.'
The swoop for versatile Boulahrouz has raised doubts about the future of William Gallas, who says he wants to leave the club.
Gallas, who is out of contract next summer, has been frozen out by boss Jose Mourinho since returning late for pre-season.
Kenyon said: 'He is not a direct replacement for anybody. We have moved players out this season and the squad will retain the same sort of size.'
Boulahrouz has a reputation for his fearsome tackling in the German league and is nicknamed 'Khalid the Cannibal'.
He watched Chelsea's 3-0 win against Manchester City on Sunday and hopes Premiership referees will understand his style.
Boulahrouz, who has 15 caps for Holland, said: 'I played in the Bundesliga and it was a little bit of a problem with the referees.
'I saw the game on Sunday. It was very aggressive and I love the tackling.
'I've played central defender for the last couple of years. That's the position where I can show all my qualities. But right-back is not a problem for me.
'I haven't played a lot of games in pre-season but I am fit and I am okay. I know what to do as a defender. That's the most important thing.
'I am happy to play for Chelsea, the biggest club in the world, and I will try to give my best and play with my heart on the pitch.'