Just yet, nipping at heels, cool heels

KKR fielded a new-look side for their match against Punjab. Manoj Tiwary, Ajit Agarkar, Ashok Dinda, Iqbal Abdulla and David Hussey all came into the starting eleven. Tiwary was impressive with the bat and Agarkar with the ball while the other three had an ordinary match. Owais Shah was the man left out for Hussey and is unlikely to be back in the side just yet, but Hussey will be feeling the pressure to perform with Shah nipping at his heels.

Ishant Sharma and Charl Langeveldt are both bowlers-in-waiting. Sharma may have to cool his heels for a while longer after disappointing in the first few matches, but Langevedlt's inclusion should be given some thought. Against the likes of Sehwag, Warner de Villiers, McDonald or Dilshan, Langevedlt's death bowling may prove vital. That would mean leaving Shane Bond out which doesn't seem like an option, since KKR will want to set up an opening clash between Bond and Warner and Sehwag, similar to the one they will be expecting between Gayle and Delhi's opening bowlers.

Please explain to me the emboldened parts.
Though I guess "cool his heels" means figuratively "he has to wait longer time given his poor performances in the past few matches".