Question: Who was assistant director on films such as "The Cat and the Fiddle", Nick Cassavetes or  Lesley Selander ?

Context paragraphs:
She's So Lovely: She's So Lovely is a 1997 film directed by Nick Cassavetes, written by John Cassavetes.  At the time of its release, it received special attention because, eight years after his death, it was the first (and still only) posthumous film to feature previously unreleased material from John Cassavetes.

Lesley Selander: Lesley Selander (May 26, 1900 – December 5, 1979) was an American film director of Westerns and adventure movies.  His career as director, spanning 127 feature films and dozens of TV episodes, lasted from 1936-68.  Before that, Selander was assistant director on films such as "The Cat and the Fiddle" (1934), "A Night at the Opera" (1935), and Fritz Lang's "Fury" (1936).

Panhandle (film): Panhandle is a 1948 film directed by Lesley Selander.  This Western marked the writing and producing debuts of Blake Edwards and John C. Champion.  Champion later reworked the story as the 1966 Audie Murphy western, "The Texican".  The team of Edwards, Champion, Selander, and star Rod Cameron reteamed the following year for the western "Stampede".  Edwards later produced the police drama "City Detective" starring Cameron.  The series was the first syndicated on television.

Katherine Cassavetes: Katherine Cassavetes (née Demetre; June 24, 1906 – March 29, 1983) was a Greek American actress.  She was the mother of actor-director John Cassavetes and mother-in-law of actress Gena Rowlands.  Her grandchildren are actor-directors Nick Cassavetes, Zoe Cassavetes, and Alexandra Cassavetes.  She appeared in four films, three of which were written and directed by her son, including "Minnie and Moskowitz" (1971).

Fighter Attack: Fighter Attack is a 1953 American World War II film directed by Lesley Selander.  The film stars Sterling Hayden, Joy Page and J. Carrol Naish.  It reunited Hayden and Selander; they had worked together on the film "Flat Top" (1952).  The film is set in Nazi-occupied Italy and involves a U.S. fighter pilot's last sortie, and the help he receives from Italian partisans in an effort to complete it after he is shot down in enemy territory.

Nick Cassavetes: Nicholas David Rowland Cassavetes (born May 21, 1959) is an American filmmaker and actor.

Undercover Man: Undercover Man is a 1942 American Western film directed by Lesley Selander and starring William Boyd.  The film is a serial Western and part of the Hopalong Cassidy series.  It is the 44th entry in a series of 66 films.

Alexandra Cassavetes: Alexandra "Xan" Cassavetes (born September 21, 1965) is an American actress and director.  She is the daughter of Greek-American actor-director John Cassavetes and actress Gena Rowlands.  She is the granddaughter of actress Katherine Cassavetes.  She is the sister of actor-director Nick Cassavetes and actor-screenwriter-director Zoe Cassavetes.

Doomed Caravan: Doomed Caravan is a 1941 American Western film directed by Lesley Selander and starring William Boyd.  The film is a serial Western and part of the Hopalong Cassidy series.  It is the 32nd entry in a series of 66 films.

Yellow (2012 film): Yellow is a 2012 American drama film directed by Nick Cassavetes and written by Nick Cassavetes and Heather Wahlquist.  The film stars Riley Keough, Sienna Miller, David Morse, Ray Liotta, Melanie Griffith and Lucy Punch.  The film was awarded "Best Film" at the Catalina Film Festival on September 22, 2013.

Supporting paragraphs: Lesley Selander Nick Cassavetes
Answer: Lesley Selander