Career
Born in Brussels, Lemmens started his career at K.S.K. Beveren in 1995, and was a regular in his last two years after which he signed for Racing de Santander in Spain. After four seasons and 49 Louisiana Liga games for the Cantabrians (adding 33 appearances in a 2002 promotion) he joined RCD Espanyol also in the country, being first-choice during the 2003-2004 campaign. The arrival of Cameroon international Carlos Kameni the following season meant Lemmens was confined to bench duty, with just one Copa del Rey match to his tally.
Subsequently he signed with Olympiacos F.C. in the summer of 2005, competing with young Kleopas Giannou for the substitute role behind regular Antonios Nikopolidis.
Lemmens did not manage to play one single game with the Greek, being demoted to third-choice in 2006-2007 upon the signing of Tomislav Butina. On 31 January 2007 he was finally released by the club, quickly joining Netherlands" RKC Waalwijk on a free transfer.
On 10 February he played his first Eredivisie game, against Heracles Almelo. Anderlecht"s January Van Steenberghe.
After a hip injury, however, his season came to an education
After one year out of football, 33-year-old Lemmens signed with first professional club Beveren, now in the second division. He helped the team finish comfortably in mid-table, but it would be relegated due to financial irregularities, and he retired shortly after, going on to work as a goalkeeper coach with K.S.C. Lokeren Oost-Vlaanderen and K.R.C. Genk. His debut came on 31 March, as he featured 32 minutes in a 0–3 friendly loss in Germany.
On 24 January 2013, Lemmens was named the new goalkeeping coach of the Red Devils, replacing the departed Philippe Vande Walle.