Under the guidance of chief creative officer John Lasseter, Pixar Animation Studios has reigned supreme for 18 years as masters of the computer-animated fable.

Toy Story, Finding Nemo and The Incredibles affirmed animation as a serious art form capable of exceeding live-action blockbusters at the box office and Up and Toy Story 3 were both nominated as Best Picture as well as Best Animated Feature at successive Academy Awards.

In recent years, Pixar has lacked some of its trademark innovation, returning to past glories for inspiration including a lack lustre sequel to Cars and the forthcoming Finding Dory.

Monsters University continues that trend, conjuring a back story to the enduring friendship of Mike Wazowski (voiced by Billy Crystal) and James P Sullivan aka Sulley (John Goodman) from Monsters, Inc..

In the colourful and fast-paced prequel, director Dan Scanlon harks back to Mike's childhood when the six-year-old ignites his desire to become a scarer.

Many years later, Mike excitedly heads off to university to realise his dream.

He befriends shy roommate Randall Boggs aka Randy (Steve Buscemi) and impresses his teachers by regurgitating facts from textbooks.

However, classmate Sulley gets all of the attention and is courted by the Roar Omega Roar fraternity and its dashing president, Johnny Worthington (Nathan Fillion).

Eventually, Mike snaps and declares war on Sulley: "I am going to scare circles around you this year!"

The rivals' fates rest on an end-of-term exam, which must be passed or Dean Hardscrabble (Helen Mirren) will expel them from the course.

She expects Mike to fail, telling him coldly, "What you lack simply cannot be taught. You're just not scary."

Unperturbed, he joins forces with the misfits from Oozma Kappa fraternity - tentacled mature student Don (Joel Murray), lovably naive Scott Squibbles (Peter Sohn), conjoined siblings Terri (Sean Hayes) and Terry (Dave Foley) and purple-striped extrovert Art (Charlie Day) - to prove that every underdog has his day.

Monsters University boasts the same appealing cocktail of comedy, action and touching friendship as its predecessor, including some lively supporting performances.

Dialogue zings and Crystal and Goodman ease back into their roles as if they were putting on a favourite pair of old slippers.

The script conceals few surprises - we know Mike and Sulley must end up friends by the timeframe of Monsters, Inc. - but there are some pleasing narrative detours, and the rivalry with Mirren's authoritarian creates a frisson of dramatic tension.

Like previous Pixar releases, the main feature is preceded by a short.

In this instance, it's The Blue Umbrella directed by Saschka Unseld, a delightful six-minute love story captured in dazzling photorealistic animation, which recounts the first flushes of romance between blue and red umbrellas on a rain-lashed city street.