David Turnbull helped himself to a hat-trick as Celtic showed 10-man St Mirren no mercy in a 6-0 thrashing at Parkhead.

Saints boss Jim Goodwin had to watch the cinch Premiership match on a stream from his house after testing positive for Covid-19 in midweek and he must have winced at the punishment handed out by the home side in the first half.

Israel international Liel Abada fired a shot through Buddies keeper Jak Alnwick in the 17th minute and by the time the 19-year-old winger had headed in a second five minutes later, Saints midfielder Alan Power had been given a straight red card for a foul on Turnbull, who grabbed a double before the break.

Returning striker Odsonne Edouard added a fifth in the 62nd minute and Turnbull completed his hat-trick in the closing stages to complete a sixth win in a row for Ange Postecoglou's rejuvenated Hoops.

Celtic face AZ Alkmaar in their Europa League play-off tie in the Netherlands on Thursday night with a 2-0 lead from the first leg before the first Old Firm game of the season against Rangers at Ibrox next Sunday and they could hardly be in better form.

There was a boost for Hoops before the game when the club announced it has reached agreement with Legia Warsaw for the transfer of Croatian defender Josip Juranovic on a five-year deal.

It was another step forward in Postecoglou's rebuild which continued against St Mirren, who were overwhelmed.

Saints assistant Lee Sharp and goalkeeping coach Jamie Langfield were guiding the visitors and in the fifth minute they watched Turnbull's drive from the edge of the box crash off Alnwick's left-hand post.

It was all hands to the pump for the Buddies but a costly five-minute spell left them reeling.

Abada's angled drive from just inside the box flew past Alnwick, who should have done better, before Power lunged into Turnbull near the touchline and was sent packing by referee Willie Collum.

Abada then headed in a cross from left-back Greg Taylor in the 22nd minute and there was no way back for the bruised Buddies.

St Mirren striker Curtis Main did have the ball in the net in the 27th minute following a rare attack but was ruled offside before Turnbull rifled in a 20-yard drive before Japanese attacker Kyogo Furuhashi volleyed over the bar from close range.

The visitors could find little respite.

In the 38th minute, Edouard flicked a shot against the bar and over from close range but the fourth arrived soon enough with Turnbull knocking the ball in from six yards after Alnwick had parried out a cross from Abada.

Celtic's dominance was unshakeable. Turnbull's long-range effort escaped the right-hand post and Alnwick stuck out a leg and denied Furuhashi, who then set up Edouard to beat the Paisley keeper from six yards after his first attempt was blocked by defender Conor McCarthy.

With imminent tests in mind, Postecoglou replaced captain Callum McGregor and Furuhashi for Ismaila Soro and Tom Rogic in the 67th minute and moments later the Australia international was denied by Alnwick.

But with six minutes remaining, Rogic played in Turnbull to poke in his third from eight yards.