Adrian Newey is the archetypal Formula 1 boffin, Ross Brawn the tactical brains who masterminded Michael Schumacher's string of titles.
The two Britons' rivalry was a thread through the 1990's and the first half of this decade. Now, after a brief lull, it has resurfaced and is as fierce as ever.
The two old opponents are back at the top in new livery while Newey's former employer McLaren struggles for pace and Brawn's ex-team Ferrari battles to recover from its worst start to a season.
"Our paths crossed consistently over the years," Brawn agreed at last weekend's Spanish GP where his Brawn cars took the chequered flag in a 1-2 ahead of the Red Bull cars designed by Newey.
"I was sort of relieved that Newey had gone into a bit of a quiet period until this year - but now he's back with a vengeance."
The former Honda team to which Brawn gave his name after a management buy-out has won four of the five races so far this year and is leading the championship by a healthy 29.5 points.
Its closest challenger, the only other team to have won this year, is Red Bull with a strikingly quick car.
Newey said: "We do seem to keep clashing on the track, which is great." His calm and thoughtful exterior masks a passion for speed that has given his employers a few jitters over the years when he has raced some of his classic sports cars.
Brawn and Newey were briefly workmates at Force, the Haas-Lola team which entered in 1985 and 1986, but since then have been on opposing sides.
Brawn trained with the British Atomic Energy Research Establishment then entered F1 as a machinist with Williams but had left long before Newey arrived as chief designer in 1990 from the short-lived Leyton House team.
Newey helped design the Williams cars that took Nigel Mansell and Alain Prost to the titles in 1992 and 1993 respectively while Brawn took on the technical director's role at Benetton in 1991.
In 1994 and 1995 the pendulum swung Brawn's way with Schumacher's first two titles for Benetton.
Newey's cars won four Drivers' titles and five Constructors' crowns in his time at Williams but he moved to McLaren as technical director in 1997.
FIVE CONSECUTIVE TITLES
At the end of 1996 the softly-spoken 'Big Bear' Brawn, who has a penchant for munching bananas on the pits wall, followed Schumacher to Ferrari and the stage was once again set for him and Schumie versus Newey.
Newey's McLaren MP4-13 won in 1998 and 1999 with Mika Hakkinen while Brawn's Ferrari team won the Constructors' championship six years running from 1999-2004 and Schumacher won five consecutive titles from 2000.
By the time Brawn left Ferrari, taking a year out to travel the world and go fishing when Schumacher retired at the end of 2006, his Italian employer had enjoyed its most dominant period.
In 2009 both men have benefited from a radical change in the rules and the fact that their teams were not competitive in the previous year, giving them more time for innovative approaches.
"I like these big rule changes, I find them stimulating," said Newey, who joined Red Bull in 2006 and designed the Toro Rosso that Sebastian Vettel drove to victory in Italy in 2008 before winning with Red Bull in China in 2009.
'NOT ON DRAWING BOARD'
"I've known Adrian a very long time and I'm a huge admirer of his work," said Brawn, who could be found only a few hours after the Barcelona win queuing up with F1 fans and holidaymakers for a budget flight home.
"He works completely differently to me," added the Manchester-born engineer who joined Honda as team principal in 2008 only for them to pull out in December.
"I'm not on a drawing board any more. My approach is more about harnessing engineers and helping them understand what they need to do and try to manage the situation.
"Adrian is much more hands-on and is coming up with stuff himself." - Reuters