Australia’s Marcus Fraser sits one shot behind in fourth, with a host of players sitting four and five-under.
A bout of flu ruled Colsaerts out of the KLM Open but it appears spending time recuperating at home has done the Belgian well.
"Nothing beats being back home with your mum looking after you," Colsaerts told the Associated Press.
Retief Goosen marked his return from a back injury with a two-under 70 after four months out.
The tournament finishes on September 22.
Scores after first round
Ricardo Gonzalez (Argentina) 65
Nicolas Colsaerts (Belgium) 65
Maximilian Kieffer (Germany) 65
Marcus Fraser (Australia) 66
Steve Webster (Britain) 67
David Higgins (Ireland) 67
Francesco Molinari (Italy) 68
Simon Thornton (Ireland) 68
Joachim Hansen (Denmark) 68
Richard Finch (Britain) 68
Seve Benson (Britain) 68
James Kingston (South Africa) 68
Jorge Campillo (Spain) 68