An illness prevented Merckx from taking part in the Milan-San Remo at the start of the 1973 calendar. During a span of nineteen days, Merckx won four classics including Omloop Het Volk, Liege-Bastogne-Liege, and Paris-Roubaix. He decided to race the Vuelta a Espana and the Giro d'Italia, instead of racing the Tour de France. He won the opening prologue of the Vuelta to take an early lead. Despite Ocana's best efforts, Merckx won a total of six stages on his way to his only Vuelta a Espana title. In addition to the general classification, Merckx won the race's points classification and combination classifications.  Four days after the conclusion of the Vuelta, Merckx lined up to start the Giro d'Italia. He won the opening two-man time trial with Roger Swerts and the next day's leg as well. Merckx's primary competitor, Fuente, lost a significant amount of time during the second stage. He won eighth stage that featured a summit finish to Monte Carpegna despite Fuente attacking several times on the ascent. Fuente tried attacking throughout the race of the race, but was only able to make time gains on the race's penultimate stage. Merckx won the race after leading from start to finish, a feat only previously done by Alfredo Binda and Costante Girardengo. He also became the first rider to win the Giro and Vuelta in the same calendar year.  The UCI Road World Championships were held in Barcelona, Spain in 1973 and contested on the Montjuich circuit. During the road race, Merckx attacked with around one hundred kilometers left. His move was marked by Freddy Maertens, Gimondi, and Ocana. Merckx attacked on the final lap, but was reeled in by the three riders. It came down to a sprint between the four, of which Merckx came in last and Gimondi in first. Following the road race, Merckx won his first Paris-Brussels and Grand Prix des Nations. He won both legs of A travers Lausanne, as well as the Giro di Lombardia, but a doping positive disqualified him. He closed the season with over fifty victories to his credit.

Answer this question "How did he do in other parts of the race?" by extracting the answer from the text above.
Despite Ocana's best efforts, Merckx won a total of six stages on his way to his only Vuelta a Espana title.