Brendan Rodgers once again shuffled his squad with their upcoming Old Firm clash against Rangers on January 2nd, which will be broadcast live on Sky Sports, at the forefront of his mind.
They dominated from kick-off and Nicolas Kuhn fired in the opener on the half-hour, with Kyogo Furuhashi adding a quick second-half double as Simo Valakari's side struggled to deal with the tempo.
Daizen Maeda got on the end of Paulo Bernardo's cross just minutes after coming on to put the Hoops 4-0 up as they extended their lead over Rangers - who drew 2-2 at Motherwell on Sunday - at the top of the table to 14 points.
A fourth straight defeat for St Johnstone leaves them three points adrift at the bottom.
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