Celtic have now lost five of seven matches under Nancy, the latest of which came on Tuesday as they were played off the park at Fir Park.
While Nancy’s side were chasing Motherwell shadows, Rangers were seeing off the challenge of St Mirren, who themselves dispatched Celtic at Hampden earlier this month in the League Cup final.
Thelo Aasgaard nodded home Jayden Meghoma’s cross before half-time and Emmanuel Fernandez converted Youssef Chermiti’s excellent ball into the box to make it two in the second half.
St Mirren fought back and were frustrated not to take a point with Mikael Mandron’s bundled goal coming after Marcus Fraser had missed from the penalty spot.
Rohl was pleased with his team’s performance, but stressed the need to maintain their good form if they are to challenge for the title.
“We have reduced the gap to three and six points [to Celtic and Hearts], but it’s nothing in football,” he said.
“It’s about next, next, next. If we can carry on this way, we will have a good second half of the season.
“If you take a lot of wins and make a lot of things right, you come in positions where you can play for something.”
On the trip across Glasgow to face Celtic, Rohl believes they are ready for the “huge” test.
“Our belief is there,” he said. “We go with confidence. It’s a huge game, but we are prepared. It’s important we are strong. If we do this, we will have a fantastic game.
“It was a good finish to the year and now we have hopefully a good start in the year.”