O is for...

As uefa.com Action's A to Z countdown to the UEFA Champions League final on 25 May continues, it is time for some great Os.

Lars-Christer Olsson is the highest operational management official within UEFA. He is responsible for the management of the UEFA administration at its headquarters in Nyon, Switzerland. Previously he was tournament director for EURO '92 in Sweden and worked as a FIFA expert in administration in 1999.

Mr Olsson was born in Sweden in 1950, joined UEFA in 2000 as director of professional football and marketing and succeeded Gerhard Aigner as Chief Executive in January 2004. As UEFA CEO, Mr Olsson attends meetings of the UEFA Executive committee as well as meetings of other UEFA committees, taking an advisory role in the deliberations.

The Champions League has seen its fair share of own goals over the years, with few more memorable than Stig Johansen's excellent headed finish against his own goalkeeper as Helsinborgs BK slumped to a 6-1 defeat against Rosenborg BK in September 2000. If he had scored it at the other end, it would have been a beauty.

VfB Stuttgart's Fernando Meira turned the ball past his own keeper in a pivotal game against Chelsea FC in 2003/04, while Arsenal FC's Pascal Cygan was credited with an own goal as Loukas Vintra's shot took a huge deflection off him to give Panathinakos FC a 1-1 draw at Highbury this season.

While the 22 players on the field are the most important element of football, we would not have a game if it were not for the officials. UEFA has some of the best match officials in the world, all trained to as high a standard as the players themselves.

Referees cover an amazing amount of ground during 90 minutes so fitness is a vital part of their game. The assistant referees too have a vital part to play - their main functions are to signal for throw-ins and watch for offsides and assist the referee in any borderline decision making.

These three officials are backed up by a fourth official on the sidelines. He is there in case of an injury to the referee or his assistants, but his main task is to oversee substitutions, check paperwork and keep the coaches inside their technical areas.