At 17, McEachran became the first player to appear in the Champions League having been born since the European Cup was repackaged in 1992, making an assured senior debut in the 4-1 win at MSK Zilina.
It caught his parents, Mark and Julie, on the hop as they watched the game on TV at home in Oxfordshire.
They did not make the 1,000-mile trip to Zilina, fearing their boy was only travelling for the experience, and McEachran's proud mum admitted to the Mirror: "We were stunned when we saw Josh standing by the touchline, ready to come on.
"He has been with Chelsea since just before his eighth birthday, so you can imagine the pride in our household that he has made it into the first team.
"We have always supported Josh wherever he has played, whether he was winning the FA Youth Cup last season or playing for England's Under-17 team, and with hindsight of course wish we could have been there to see him make his Chelsea debut.
"It would have been a long way to travel just to watch him sit on the bench or in the stands, but I managed to speak with Josh on the phone briefly after the game and I told him how proud the family were of his performance."