This was West Ham's third match in six days and David Moyes redeployed seven of the players who drew with Tottenham Hotspur on Thursday, the only non-regulars being Reece Burke and Josh Cullen, a pair of 21-year-olds recently returned from loan stints at Bolton Wanderers. "For the first half especially, we didn't compete at all".
West Ham are 15th in the top flight after something of an upturn in form since Moyes' arrival, but the Hammers are hardly invulnerable to disaster.
League One promotion chasers Shrewsbury grew more and more into the contest, however, and had a couple of big chances to open the scoring.
Ouch! West Ham's Josh Cullen loses a tooth!
And Shrewsbury-born Hart admitted he needed help in the first half.
"I was a substitute against BATE Borisov in a Europa League game and I was called to get stripped to come on - but I didn't have any shinnies".
Mat Sadler's shot in the 35th minute packed much more power and demanded a solid save from Hart, who had to repeat it moments later when Alex Rodman let fly from a similar position at the left-hand corner of the West Ham box. I don't think it affected my Everton career, though, as I knew I would be released.
Despite the lack of goals, the game had exhibited everything that is traditionally good about the FA Cup, with Shrewsbury, at the very least, fully deserving their replay at the London Stadium, likely to be a week Tuesday. Shrewsbury, neat and compact as they have been this term, looked for an opening of their own, with Shaun Whalley asking questions of the Hammers rearguard with an exquisite angled dead-ball which was scrambled to safety. I felt they were on the front foot and we weren't. We were up on them and rattling them the whole game.