For the fourth year running, Atlas F1 is going to keep an eye on the battle between teammates throughout the season with a simple measurement: we compare the qualifying times of each driver against his teammate's result. After every Grand Prix, we will show how teammates have fared up against each other, and where they are overall since the beginning of the season. At the end of the season, the World Champion of Qualifying Differentials will be elected - the driver who was most beaten by his teammates, in seconds. Only those who participate in at least 15 of the 17 rounds are eligible for the coveted crown; and for those who made the efforts and participated in all 17 races, the best and worst result will be scrapped.

With sixteen qualifying sessions completed for 2001, the differentials are on a roll! Let's see which drivers deserve bragging rights.

USA Notables

• Setting the Record Straight. While Sauber's Nick Heidfeld equalled his previous best ever qualifying position, Minardi sensation Fernando Alonso set his best qualifying result so far - 17th on the grid. The achievement is only further highlighted if you take into consideration who he outqualified: one Jacques Villeneuve, the 1997 Formula One World Champion.

• Villeneuve. Speaking of Jacques: the French-Canadian had one of his worst qualifying ever, 18th being his worst position since the 1999 Brazilian Grand Prix.

• Irvine. Whatever Niki Lauda told Eddie Irvine after the Italian Grand Prix, it worked: the Ulsterman outqualified teammate Pedro de la Rosa for the first time since the French Grand Prix, some six races ago. The pair are now equal on six each in the 'outqualifying your teammate' match.

• Hakkinen. Mika Hakkinen's penalty, scrapping his fastest time in qualifying and thus effectively moving him from second to fourth on the grid, also affected his gap to teammate David Coulthard: whereas originally the gap was 0.555, the gap is now 0.191. Still, in the overall averages through the US Grand Prix, Hakkinen remains ahead of Coulthard and with only one Grand Prix to go, there's hardly any chance the order will change for 2001.