Round four of the 2009 Motocross World Championships takes place at Valkenswaard this weekend, where Toni Cairoli and Gautier Paulin will be aiming to extend their respective MX1 and MX2 title lead.

After three different winners and three different championship leaders in the first three grands prix, Cairoli's first victory as a full time MX1 rider has propelled the Yamaha star to the top of the standings by four points over Suzuki's Ken de Dycker.

de Dycker won at Valkenswaard one year ago and will surely be among the riders to beat in the deep sand, along with team-mate Steve Ramon and reigning champion David Philippaerts - all of whom are yet to taste GP victory this season.

Philippaerts provided Cairoli's closet opposition last time out, while Monster Yamaha team-mate Josh Coppins - winner in Bulgaria - will be looking to get his championship challenge back on track at Valkenswaard, where he won in 2007 in front of KTM's Jonathan Barragan.

Red Bull KTM Factory Racing's Max Nagl took third behind de Dycyker and Ramon last season. A hand injury has hampered the German's results so far but he is expected to come back stronger after the week break following Istanbul.

Honda's hopes are being carried by Martin Honda's Strijbos and LS Motors' Clement Desalle.

Desalle is now ninth in the championship after he took his maiden podium at Faenza but Strijbos is building confidence after fifth overall at Istanbul.

On the other hand CAS Honda's Billy Mackenzie has had a tough season beginning but the Brit looks forward to Valkenswaard where he was fourth in 2008 - his best GP finish since he joined the factory Honda squad in 2008.

In MX2, Paulin of Kawasaki Bud Racing PSM has been leading the championship since his maiden GP win at the Faenza season opener and enters round four aiming to continue his podium streak.

Another rider chasing such a consistent record is NGS' Marvin Musquin who is just five points behind Paulin. The French duo are trying to pull away from the rest of the field, as third placed Davide Guarneri currently has a 30 point gap from Paulin.