Alfa Romeo continued to set the pace, but Ferrari came close to toppling the champions. Mechanical problems had robbed him the previous year,but now Juan Manuel Fangio was dominant and claimed his first title.
For 1951 Alfa Romeo broke up the "three Fs" team, replacing Fagioli with 48-year-old Felice Bonetto. Froilan Gonzalez, who had previously driven a Maserati, joined Ascari and Luigi Villoresi at Ferrari. The stocky young Argentinian, known as the "Pampas Bull", was to become a major force during the season.
The championship was expanded to seven races, with Monaco missing and events in Germany and Spain added. This time the series began in Switzerland, and in soaking conditions Fangio scored a fine win. Meanwhile, a promising young Englishman made his debut in a British HWM, qualifying 14th and finishing eighth. His name was Stirling Moss.
Farina and Fangio dominated the Belgian Grand Prix at Spa, but when Fangio pitted, a rear wheel stuck on and his race was ruined. Farina won from the Ferraris of Ascari and Villoresi, while a fired-up Fangio set the fastest lap - but finished ninth.
Fagioli was back in an Alfa at Reims, and went on to score his first victory - but only after Fangio took over his car when his own mount had retired in a race of high attrition. Another shared car, the Ferrari of Gonzalez and Ascari, took second, ahead of Villoresi. After tyre troubles, Farina was a distant fifth.
A Ferrari win seemed on the cards, and the first finally came at Silverstone where Gonzalez put in a fine performance to take the lead from countryman Fangio when the Alfa driver pitted and stalled when he tried to rejoin. The BRM made its first championship appearance, with Reg Parnell taking a promising fifth and Peter Walker seventh.
Ferrari proved the dominant force at the Nurburgring, the first champ-ionship race held on the long, tortuous circuit. Ascari notched up his first win, despite a late stop for rear tyres. Fangio, who required an extra scheduled fuel stop, took second for Alfa. Third to sixth places were filled with Ferraris, while Farina retired with gearbox trouble.
Monza was the penultimate round this year, and Ascari and Gonzalez celebrated a fine one-two for Ferrari in front of the home crowd. Alfa had a much-modified car, the 159M, and Fangio was battling for the lead until a tyre failed. His storming recovery drive ended with engine failure. Farina retired early, but took over Bonetto's car and eventually earned third place.
The final race at Pedrables in Spain proved to be Alfa's swansong. Despite his Monza retirement, Fangio led Ascari by 28 points to 25 going into the race, and a dominant win secured Juan Manuel's first crown. The Ferraris suffered tyre troubles, with Gonzalez and pole man Ascari taking second and fourth, split by Farina's Alfa. At the end of the year Alfa withdrew from grand prix racing, unable to finance a new car to challenge Ferrari in 1952. Partly in response to Alfa's Romeo's departure, the Fédération Internationale de l'Automobile announced that, for 1952, the World Championship would run to less powerful Formula Two rules. It was hoped this would encourage a wider variety of cars and avoid a Ferrari walkover.