With teammate Jamie Roberts already a doubt for the Six Nations opener against Ireland on February 6, Jenkins gave Gatland a further headache.
With Scarlets fly-half Rhys Priestland and Newport Gwent Dragons flanker Dan Lydiate already joining the casualty list in Saturday's European fixtures the weekend was already a sour one for Gatland.
And with less than two weeks until the Six Nations gets started the Kiwi coach was given more bad news with Jenkins' setback.
Wales' pre-Six Nations camp kicks off in Poland today and Blues backs coach Gareth Baber admitted Jenkins' diagnosis is not yet clear.
"It is very early to say," said Baber.
"Over the next 24 to 48 hours we will get more information. I think he has tweaked a ligament in his knee.
"I am not sure what 'tweaked' means, to be quite honest with you, whether it means he is just hurting a little bit and it will sort itself out, or anything further."
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