Indian pace spearhead Zaheer Khan is unlikely to play in the first cricket Test of the three-match series against South Africa. Zaheer is struggling with a hamstring injury and bowled only a few overs at the nets during the two training days in Centurion. Skipper Mahendra Singh Dhoni said on Wednesday that either Jaidev Unadkat or Umesh Yadav may earn their first Test cap if Zaheer happens to miss the opening Test on Thursday.