Thomas hit the post with his conversion and a van Gisbergen penalty settled the away side's nerves as they held on despite a late Leeds pressure.
BBC: Leeds 8-17 Wasps
2.
Shortly after, L'Estrange powered over and Ah Van added the conversion to leave the scores level at the break.
BBC: Catalan Dragons 8-8 Bradford Bulls
3.
After visiting winger Richard Haughton had quickly cancelled out home prop Joe Marler's early try, full-back Mark van Gisbergen's conversion put Wasps ahead.