Chelsea signed off with a perfect record in the league phase of the Conference League as Marc Guiu scored a first-half hat-trick to seal a 5-1 demolition of League of Ireland side Shamrock Rovers at Stamford Bridge.

The 18-year-old former Barcelona striker is yet to start for head coach Enzo Maresca in the Premier League but selected for the fourth time in Europe he demonstrated a poacher’s instinct to bury the visiting side, twice intercepting passes back to the goalkeeper to score before glancing in a fine header for his third.

Kiernan Dewsbury-Hall also netted, as did Marc Cucurella for the second time in as many matches, as Chelsea confirmed what had long been apparent – they have been far too strong for the teams they have faced in the first phase of Europe’s third competition.

The defeat was a first in Europe this season for Shamrock who left west London with the consolation of a place in February’s play-off round, as well as with the memory of Markus Poom’s goal that briefly levelled things at 1-1 in the first half and offered the glimpse of a major upset.

Chelsea enjoyed more than 80 per cent possession during the first 25 minutes but it took a disastrous defensive error for them to take the lead.

Renato Veiga hoofed a looping ball forward for Tyrique George to chase. Darragh Burns reached it first, but his wayward header back to his goalkeeper was woefully misjudged allowing Guiu to steal in and nod Chelsea in front.

The visitors responded with no little courage. Chelsea goalkeeper Filip Jorgensen flew towards his top corner to claw away a Johnny Kenny drive as Shamrock broke. From the resulting corner, the Premier League high-flyers briefly allowed their supporters to dream.

Dylan Watts’ cross was headed out to the edge of the box where Estonia international Poom – whose father played here for Derby during the nineties – was waiting to smash it back goalward, his drive flicking off the heel of Cesare Casadei and whizzing past Jorgensen.

It was a memorable moment for Shamrock on their European adventure, which made the manner in which they conceded the next goal all the more bitter.

Daniel Cleary offered Guiu another gift. His pass back to Leon Pohls was under-hit and got nowhere his goalkeeper, but had the perfect trajectory for Guiu to get there first and nip around Pohls to make it 2-1.

The hosts scored a third after 40 minutes. Cucurella threaded a ball through for Christopher Nkunku who was wrestled to the ground by defender Roberto Lopes. Before the referee could blow for a penalty Dewsbury-Hall had driven the loose ball into the bottom corner for his second Chelsea goal.

Guiu completed his hat-trick with the last action of the first half, rising highest inside the box to glance Noni Madueke’s cross into the corner.

Cucurella cut inside his defender before driving inside the near post to make it 5-1 just before the hour.

Maresca sent on academy graduates Samuel Rak-Sakyi, Harrison Murray-Campbell and Harvey Vale for a taste of European football, then 18-year-old winger George nearly opened his Chelsea account, denied on the line by Rovers captain Lopes.