1991 Formula One World Championship  The 1991 FIA Formula One World Championship was the 45th season of FIA Formula One motor racing. It featured the 1991 Formula One World Championship for Drivers and the 1991 Formula One World Championship for Constructors, which were contested concurrently over a sixteen-race series that commenced on 10 March and ended on 3 November. Ayrton Senna won his third and last Drivers' Championship, and McLaren-Honda won their fourth consecutive Constructors' Championship. Senna won seven of the sixteen races; his main challenger for the title was Nigel Mansell, who won five races in his first season back at Williams. Senna's fierce rival Alain Prost failed to win a race with Ferrari and was fired before the end of the season due to a dispute with the team. 1991 also saw the debuts of future world champions Michael Schumacher and Mika Häkkinen, as well as the retirement of three-time champion Nelson Piquet.  , this is the last season to be won by a South American racing driver. The following teams and drivers competed in the 1991 FIA Formula One World Championship. Three teams that started the 1990 season would not make the start of the 1991 season: EuroBrun had failed to complete the season. Onyx Grand Prix also pulled out during 1990, but went as far as designing a 1991 car before finally folding, while the absence of Life, a team that failed to prequalify for every race, surprised no-one. The Osella team was now Fondmetal, though driver Olivier Grouillard was retained along with the 1989 Osella car and most of the staff. The Arrows team was renamed Footwork after an investment by Japanese businessman Wataru Ohashi, President of Footwork Express Co., Ltd. There were two entirely new entrants for the 1991 season;  At the start of the season, pre-qualifying was needed for five teams: both cars of the Jordan, Dallara and Modena teams and the single entrants of the Fondmetal and Coloni teams. A change to the points system in 1991 saw the winning driver now awarded 10 points instead of 9 as previously. More significantly, points from all races would now count towards the championship, instead of only each driver's best eleven results as previously. The season started off at the Phoenix street circuit that had a modified layout to make it more of a challenge to drivers. Senna took pole ahead of Prost, Patrese, Mansell, Piquet and Alesi.