First Derksen added a level par 71 to his dazzling opening 63 to reach halfway in the Alstom Open de France at eight under par.
Then he sat down to watch the Netherlands beat Brazil 2-1 in the World Cup quarter-finals - as he had predicted beforehand.
The game was screened during a thunderstorm delay of nearly two-and-a-half hours at Le Golf National and when played resumed in the evening Derksen led by two from Indian Jyoti Randhawa, defending champion Martin Kaymer and Spain's Alejandro Cañizares.
"I'll definitely be watching," Derksen said straight after his two birdie, two bogey effort. "The result, I've got a bet with Jos [Luiten] going, I said 2-1 for Holland and he said 3-1. We both think Holland wins, that's the most important thing."
Of his round he added: "I think the irons weren't as close as yesterday. I played very good the first 12, 13 holes, had lots of chances but didn't convert them into birdies.
"But that was mainly because I was a little bit further away than yesterday and I didn't drive too well for the last five or six holes and got into a problem a few times and that cost me a few shots. Other than that, still satisfied, though."
Kaymer and Cañizares, who double-bogeyed the 17th after joining Derksen out in front, had nine and eight holes to complete respectively.
French star Jean Van de Velde, who in only his second event of the year began with a 66 for joint second place, set off again with a double bogey and stood two under after eight as the action got going again.
Kaymer set off again with a birdie and when he added another on the long 14th he was up with Derksen on eight under.
Canizares had moved back to seven under on the fifth, his 14th, and McIlroy matched Kaymer's second birdie to stand five under.