The Blues reckoned the brilliant midfielder - now with Spurs - was "not good enough."
So they rejected a £10million deal and instead spent £24m on Yossi Benayoun and Ramires.
A Chelsea insider revealed: "We had a call to say Jose Mourinho was ready to let Van der Vaart leave Real Madrid for around £10m and did we want him.
"But it was decided he wasn't good enough so we passed on him. That's not looking the best of decisions is it?"
Van der Vaart instead joined Tottenham for £8m on deadline day and has been an instant hit with 10 goals so far this season.
But Ramires and Benayoun have both failed to make any significant impact. Israeli Benayoun, 30, has managed six games having been sidelined since September with a ruptured Achilles.
Brazilian Ramires, 23, has struggled to come to terms with the pace and power of the Premier League.
SunSport's Chelsea source added: "Van der Vaart is just the sort of player we need - someone with flair, skill and vision.
"Our midfielders are too alike - they are strong and powerful, good athletes but not with a great deal of invention."
i think chelsea fancy south amercians.
they shouldnt have signed ramires just because of his performance at the world cup.
dutch players are actually more suitable for the premiership.
Sad
This kind of thing always happen.
I think VdV at that time preferred to join MU than Chelsea.
Yeah, there was a report that he said he wanted to play for United hoping they would come in for him but they didn't show any interest then they (his agent) went around looking for a club for him preferably with CL qualification I guess so they went to Chelsea but was rejected it seems. Thats why he ended up at Spurs at a further cut-price at the very last minute deal... Spurs earn lor, they got a player at the cut-priced deal that could even stand up to all their quality star players...