The night belonged to Kai Havertz, who scored three times. The 21-year-old striker is still adjusting to the English game but his hat-trick will give him confidence.
Tammy Abraham opened the scoring after 19 minutes and Havertz doubled the lead 11 minutes later in a first half where the home side were second best, but Frank Lampard’s team took control in the second period.
Ross Barkley added a third goal four minutes into the second half before Havertz took centre stage. The German made the most of Barnsley’s defensive deficiencies and produced cool finishes in the 55th and 65th minutes. Havertz will face tougher opponents, but he clearly has an eye for goal. His contribution to Barkley’s goal bodes well for Lampard, too, as does his growing understanding with Mason Mount.
Olivier Giroud, who replaced Havertz after the hat-trick goal, completed the scoring with seven minutes left.
Barnsley had the better of the first 45 minutes. Thiago Silva was given his debut, but the 36-year-old will take time to marshal the Chelsea back line.
Callum Styles ran at the heart of the nervous home defence and surged into the area. His held the ball too long, though, and Chelsea were able to crowd him out. Styles’ partnership with Marcel Ritzmaier down the left caused Fikayo Tomori problems. Willy Caballero had to make a fine save from Cauley Woodrow’s shot from distance. Then Aapo Halme barged into the box and was able to head towards goal, but his effort was weak and straight at Caballero.
Barnsley were the better side, but a moment of defensive sloppiness changed the game.
Michael Sollbauer looked to have killed any danger when he intercepted the ball on the edge of the box and played it out to Ritzmaier. The Austrian, perhaps conscious of Barkley lurking 10 yards away, played a first-time pass back towards goal. Abraham was on it in a moment. The striker turned a defender and kept his cool to shoot confidently past Brad Collins.
It was against the run of play and Chelsea piled on the pressure, determined to take advantage of their opponents’ error. Havertz picked out Mount in the box and the 21-year-old appeared to be picking his spot as he traversed the box. Remarkably, Mount prodded the ball just wide.
The reprieve did not last long. Mount made up for his miscue by picking up possession out wide on the left and angling a splendid pass into the area. Abraham fooled the defence by letting the ball run through his legs and Havertz timed his run perfectly to arrive unattended and score his first goal for the club.
The visiting side still showed signs of life. Styles shot just wide, Sollbauer botched a free header from a corner and Ritzmaier forced Willy Caballero to save with his legs.
At the other end Collins hesitated when contesting a high, bouncing ball with Abraham and levelled the striker. It was clumsy rather than malicious but the goalkeeper could consider himself lucky to escape with a yellow.
The fight seemed to drain from Gerhard Struber’s team in the second half. They became increasingly sloppy at the back and gifted Chelsea two more goals. Four minutes after the break Barnsley attempted to pass the ball out from the back. Styles did not realise Havertz was close by and the German slid in and poked the ball to Barkley on the edge of the box. The Englishman gratefully drove into the area and finished with a left footed shot.
Havertz now imposed himself on the game. He was on the scoresheet again quickly. Sollbauer miscontrolled the ball on the left and Mount took advantage of the mistake. He drove towards the line and crossed, Abraham flicked on the ball on and Havertz had the simple task of scoring.
His hat-trick goal was even easier. Abraham clipped the ball forward from the centre circle and Collins was tentative coming out of the area again. Havertz touched the ball around the goalkeeper and walked the ball into the net.
The German’s class was clear. He was by far Chelsea’s best performer and revelled in the room Barnsley allowed him.
Giroud completed the scoring with a fine headed but Havertz is the future at Stamford Bridge. He will score plenty of goals against much better teams.