Question: Tonino Valerii co-directed the 1973 film My Name Is Nobody with which legendary Western director?

Context paragraphs:
Go Gorilla Go: Go Gorilla Go (Italian: "Vai gorilla" ) is a 1975 Italian poliziottesco film directed by Tonino Valerii.

Sunset (film): Sunset is a 1988 American mystery action film written and directed by Blake Edwards and starring Bruce Willis as legendary Western actor Tom Mix, who teams up with legendary lawman Wyatt Earp, portrayed for the second time in a theatrical film by James Garner.  Based on an unpublished novel by Rod Amateau, the plot has Mix and Earp team up to solve a murder in Hollywood in 1929.

Tonino Valerii: Tonino Valerii (20 May 1934 – 13 October 2016) was an Italian film director, most known for his Spaghetti Westerns. Tonino (Antonio) Valerii started his film career as an assistant director on Sergio Leone's "A Fistful of Dollars", before moving on to direct by himself.  Among his best-known films are "Day of Anger" (1968) "The Price of Power" (1969), "A Reason to Live, a Reason to Die" (1972) and "My Name Is Nobody" (1973), starring Henry Fonda.

Sahara Cross: Sahara Cross is a 1977 Italian action film directed by Tonino Valerii.  It is the first Italian film to use steadicam.

The Price of Power: The Price of Power (Italian: "Il prezzo del potere" ) is a 1969 Spaghetti Western directed by Tonino Valerii.  The film stars Giuliano Gemma as the hero Bill Willer who tries to get revenge against the killers of his father while at the same time trying to prevent an assassination plot against president James Garfield (played by Van Johnson, with José Suárez playing Vice President Chester A. Arthur) in 1881.

My Name Is Nobody: My Name Is Nobody (Italian: "Il mio nome è Nessuno" ) is a 1973 Spaghetti Western comedy film.  The film was directed by Tonino Valerii and, in some scenes, by Sergio Leone.

My Dear Killer: My Dear Killer (Italian: "Mio caro assassino" ) is a 1972 giallo film directed by Tonino Valerii.  The film was referred as "one of the best films in the thriller genre" and as "one of the best, most vibrant and well designed products of Italian giallo".  It co-starred George Hilton, Patty Shepard, William Berger and Helga Line.

A Girl Called Jules: A Girl Called Jules (Italian: "La ragazza di nome Giulio" ) is a 1970 Italian drama film directed by Tonino Valerii.

Day of Anger: Day of Anger (Italian: "I giorni dell'ira" , lit.  "The Days of Wrath") is a 1967 Spaghetti Western film directed and co-written by Tonino Valerii and starring Lee Van Cleef and Giuliano Gemma, and features a musical score by Riz Ortolani.  The film credits the novel "Der Tod ritt dienstags" ("Death Rode on Tuesdays") by Ron Barker (Rolf O. Becker) as its basis, although Valerii and screenwriter Ernesto Gastaldi have attested that this credit was primarily included to appease the West German co-producers, and that although some scenes are partially borrowed from it, the film is not an adaptation of Becker's novel.

Per il gusto di uccidere: Per il gusto di uccidere (internationally released as Taste for Killing, "Lanky Fellow" and "For the Taste of Killing") is a 1966 Italian Spaghetti Western film directed by Tonino Valerii.

Supporting paragraphs: Tonino Valerii My Name Is Nobody
Answer: Sergio Leone