The new left-back had previously missed pre-season minutes, and with the countdown just six days away before Leeds herald the start of the new signing, boss Jimmy Floyd Hasselbaink is taking no chances.
He said: "He twisted his ankle a little bit and I did not want to take any risks with it."
It's all the more important Bidwell is nursed back to full health, after Jack Robinson will most definitely miss the curtain raiser.
The former Liverpool defender has been under the cosh with knee problems since he signed from Liverpool two years ago, and so far, has just a solitary Rs outing to his credit.
Robinson has picked up yet another niggle related to his knee and needs more time on the treatment table.
Striker Conor Washington is also playing catch-up in a fitness bid to throw his hat into the ring.
The Northern Ireland forward was allowed time off after his Euro 2016 efforts, and despite scoring one of the two goals that beat the Hornets, believes he might need an U21 outing or two before he reaches the demanding standards set by Hasselbaink.