"I made a mistake on the last run when I had a good feeling and could drive the vehicle better", he admitted. "I apologise for that, but that is how it is".
Reigning world champion Lewis Hamilton said it would be "interesting" to see how drivers battle for the 21 points on offer throughout the season, but his title rival Sebastian Vettel said: 'I don't expect much change.
"It's already hard when it's running smooth", he continued: "We have to stay away from kerbs, so it is not easy, especially when you are fighting to stay on track".
"I think we have a much clearer picture of the auto and also, today, it was a kind of testing as well, because we were not fighting for anything it was an opportunity for us to test things, which normally you'd be focusing more on the route you know".
"There was nothing he could have done differently", he added. "It was just bad timing, the wrong moment at the wrong time".
Robert Kubica's return to F1 is a fairytale like none other.
Williams, however, are struggling big time.
Kubica acknowledged that Williams is alone, right at the back of the field.
'I don't think it will decide a championship - could do, but I don't think it will.
Russell was happy to have come out on top against his experienced team mate, but there was no question just how far off the pace the FW42 had been looking all through the weekend.
Williams are way off pace and will need some massive developments during the season to get off that last place. Rookie Russell says Williams has discovered the problem, but it will take months to fix.
"It felt like a really good lap, driving round a mega track at full beans", he commented, his enthusiasm undimmed by the reality of Williams' performance level.
"Obviously this is the first race and the main job now is to really help the team understand the weaknesses and how to go forward", he said.
"I don't want to put numbers on it, because last year we knew early on what was the fundamental problem with the auto and for the whole year it stayed more or less the same", he said.