Nowadays, there are fixed referee trios consisting of a main referee and two assistant referees who are usually bound to the same referee during the entire competition. This has become praxis for the first time at World Cup 2006 and its previous preparation tournaments. That's why assistant referees are no lonely fighters anylonger but real teamplayers. The logical consequence is that they can be very happy to get maybe three or four matches in Brazil. This has been by far different in the past.
It was Poland's Michal Listkiewicz (above) who has established a unique record number of matches as an assistant referee (or linesman..) at the same World Cup. At 1990 World Cup in Italy, he joined a total amount of 8 matches on the sidelines including the semifinal between Italy and Argentina (refereed by Michel Vautrot, the other assistant referee was today's Referee Committee member Peter Mikkelsen from Denmark) and Germany's late final win over Argentina handled by Edgardo Codesal of Mexico, where Listkiewicz even advised his Central American boss to send off Argentine Dezotti for a violent conduct in the additional time. This record has never been beaten - the next in size is e.g. Hector Vergara of Canada with 6 matches in 2002.
Like Peter Mikkelsen, Michal Listkiewicz also joins FIFA's Referee Committee. Listkiewicz and his colleagues (e.g. Sene, Lacarne, Trentalange, Maltock etc.) accompany the referees to their matches at competitions such as youth World Cups, the Confederations Cup or even the World Cup. Check this file to read the names of the assessors active at the venue cities during the 2010 group stage matches. However, this is a bit irritating: even though their function suggests that they would really assess the referees, this is not directly the case. The real reports and match analyses are normally written and conducted at the referees' hotel by Massimo Busacca and his closer colleagues - and by the way: Pierluigi Collina will be present in Brazil to accompany the committee, too, as sources have reported.