For a certain type of sports fan, the numbers generated by the action are almost more important than the action. After tonight's semi-final against Fiorentina, while most Rangers supporters dream of glory or drown sorrows, others will be pondering how the result affects the team's UEFA coefficient.

The wealth and importance of the Champions League has shone light on the seeding system used by European football's governing body.

Draws and rankings are based on average points earned over five years' previous European campaigns, so success breeds success. If Rangers win the league and UEFA Cup, they could be as high as pot 2 for next season's Champions League draw (depending on events in other countries' leagues), which would greatly aid their hopes of reaching the knockout stages. The Ibrox club have also done Celtic and the rest of Scotland a favour by helping to pull the country's coefficient up to 10th.

With the importance of these numbers to teams and fans, you might assume UEFA would have an army of full-time statisticians updating daily an in-depth website. But the definitive guide to qualification for Europe's richest sporting event is run in his spare time by a 55-year-old man from a small city in Netherlands.

Bert Kassies' homemade site attracts millions of visitors a year. The internet's power to bring like-minded individuals together has turned a hobby into an empire. "I first got the idea somewhere between 1985 and 1990," explains Kassies in an interview conducted, appropriately, by email. "At that time I became interested why some countries had more clubs in the UEFA Cup than others.

"So I decided to write a little computer program that could calculate UEFA coefficients. But without the internet it was purely a private hobby. In 1996 we got the first dial-up internet connection to our home and after a year or so I decided to put the information on the calculation of the UEFA coefficients on a website.

"It started with very few visitors, but it attracts nowadays several millions each year."

Kassies, a systems designer for the National Aerospace Laboratory in the Netherlands, lives in Meppel, a small city halfway between Amsterdam and Groningen. He is married with three children, Maradona is his favourite player and he has been an Ajax fan "since that remarkable night in 1966 when they beat Liverpool by 5-1 in the second round of the Champions Cup". I didn't ask if he owns a potting shed.

The site has affected his personal life because of the time it takes. "But as long as it's fun, it is no problem, like all hobbies." His friends occasionally tease him, but are mostly just fascinated that such a simple website attracts so many people.

"This time of year is busy because in all countries clubs qualify for next year's European competitions," Kassies says. "But usually I don't spend more than a few hours per day on the site, because of my regular job and family life.

"The only thing I need to do is to input the match results. The ranking pages are automatically generated by a computer program. The large user base almost guarantees accuracy. If I make a mistake, I will receive many emails within a few hours to correct me."

Kassies has resisted the temptation to cash in. His simple, clear site, packed with tables, graphs, FAQs and wikis, has just a few small Google advertisements to pay for its upkeep. UEFA have not been in touch, perhaps happy to let him do the hard work unpaid.

A community has grown on the site's forums. One of Kassies' fondest memories of his hobby is the day that a long investigation into "the details on the rounding of the team coefficients that are used for seeding of draws" was finally resolved to everyone's satisfaction.

As a statistician, Kassies will have a keen interest in both tonight's semi-finals. As a Dutchman, he hopes Dick Advocaat's Zenit St Petersburg win the competition.

But football is not his life. He has "just retired" from playing volleyball and is a keen walker, keeping in-depth online records of his tours, replete with maps and pictures. He has another site, which records the sunrise and sunset times in Meppel. This is "somewhat less popular" than the coefficients site, he jokes - and unlikely to overtake it any time soon.

Big-match stats Rangers' 3-2 UEFA Cup victory over Livorno last year was the first win for a Scottish side in Italy. Fiorentina have won every home game against Scottish sides. The Ibrox side are the lowest-scoring left in the UEFA Cup, with 12 goals in 13 games. Fiorentina have scored 20. Adrian Mutu, the Romanian striker, has scored six UEFA Cup goals this season - one fewer than Scot Robbie Winters of Norway's Brann Bergen. Christian Vieri, the Fiorentina striker, has scored 27 goals in 75 European matches. Nacho Novo and Daniel Cousin have both scored 14 times in 37 UEFA competition matches. The Italians' record home win in the UEFA Cup was a 6-1 victory against IF Elfsborg in November and their heaviest home defeat is 3-0 by both Grasshopper Zurich and FC Schalke 04. Rangers' record away victory is an 8-0 win against Valletta in 1983.