under the cosh

(idiomatic) subjected to (figurative) pressure; under the gun

Example: 2011 October 2, Aled Williams, “Swansea 2 - 0 Stoke”[1], BBC Sport Wales:
  Having been under the cosh Swansea were enjoying a promising spell and Begovic had to deny Graham having a free header before Swansea's record signing secured victory with five minutes remaining.