Cristiano Ronaldo scored a first-half hat-trick as Juventus took out their Champions League frustration on Serie A strugglers Cagliari in a 3-1 away win.

The subject of transfer speculation after disappointing in the Bianconeri's European exit to Porto in midweek, Ronaldo came to the fore on Sunday with the second-fastest treble of his outstanding career.

The 32-minute blitz was enough to cast aside 17th-placed Cagliari, who had conceded all of their previous six Serie A goals after the break.

Giovanni Simeone struck back to cap an improved second-half display from Cagliari, but Juve comfortably eased to a third straight league win.

Federico Chiesa had already equalled his career-best tally of assists in a single Serie A campaign, and the winger nearly had a seventh of the season when he crossed for Ronaldo, whose header was deflected wide.

Juve's opener came from the resulting corner, Ronaldo powering in Juan Cuadrado's cross.

Alvaro Morata squandered a great chance 12 minutes later but made amends with a terrific ball for Ronaldo, who drew a rash lunge from Alessio Cragno and duly thumped home the subsequent spot-kick.

Having crafted Morata's wasted opportunity, Chiesa got the assist his performance deserved in the 32nd minute, his drilled crossfield pass teeing up Ronaldo to complete a perfect hat-trick with an arrowed left-footed finish beyond Cragno.

Cagliari started the second half brightly and, after some smart stops from Wojciech Szczesny, were rewarded when Simeone slammed home from a precise Gabriele Zappa cutback.

VAR deemed Joao Pedro not to have been fouled by Adrian Rabiot inside Juve's box soon after.

Chiesa just failed to turn in Cuadrado's centre to restore a three-goal advantage, but the visitors ultimately avoided any further scares to move within 10 points of leaders Inter.