Yusuf, 31, is likely to miss KKR's second match against Delhi Daredevils but the hard-hitting batsman is expected to return by the third game, confirmed a team official.
Sent into bat at No.5 with just a couple of overs remaining in the innings, Yusuf remained unbeaten on 4. He didn't get to bowl.
The Baroda skipper had been in good touch coming into the tournament, scoring 135 runs at 67.50 in four matches in the Syed Mushtaq Ali Trophy, at a strike rate of 182.43.
He was bought back by Kolkata for Rs 3.25 crore in the February auctions, where the franchise used a right-to-match card on him.
Yusuf's brother Irfan, who is with Sunrisers Hyderabad, tweeted as a proud uncle on Thursday: @IrfanPathan Alrightttt this is great no words can Describe the feeling.My bro Yusuf n Bhabhi blessed with baby boy I'm CHACHU now.Ya rab Tera Shukar hai.