The reason for the shock resulted from the fact The Blues already had a litany of players capable of playing in the three positions behind the striker, the arrival of a third for a fee of £3.5 million seemed bizarre.
But the winger, who had been linked with Liverpool, Everton and Tottenham Hotspur previously, is clearly one for the future - so was sent out to continue gaining first team football at Chelsea’s farm club Vitesse Arnhem.
He is over in Holland along with the likes of Lucas Piazon, Gael Kakuta and Patrick van Aanholt - as Vitesse attempt to launch an offensive on the Eredivisie title.
This weekend they faced Feyenoord in one of the games that could define their season, but Atsu started from the bench.
In fact this is not unusual, Atsu has sat on the bench for all three of his squad appearances with the side against ADO Den Haag, NEC Nijmegen and today against Feyenoord.
But at least he got some action today, entering the fray in the 77th minute.
And he had almost an immediate impact. Just five minutes later he dinked in a cross that was planted into the back of the net by Japanese international Mike Havenaar.
Unfortunately, it proved too little too late for Vitesse - who lost the game 2-1.
But hopefully Atsu has earned himself a starting spot, exactly what Chelsea want.
Here is his assist …
image: © Vincent Teeuwen