Clean sheets are the cornerstone of many a successful football team, and for sides looking to preserve their Premier League status they are just as important as goals.
Five sides who famously staged unlikely recoveries when threatened with relegation did so on the back of sudden defensive improvements.
West Ham United in 2006/07, Fulham in 2007/08, Wigan Athletic in 2011/12, Leicester City in 2014/15 and Sunderland in 2015/16 were all either bottom of the table or second from bottom with 11 matches remaining.
But all of them discovered a resilience during the run-in that helped propel them out of the bottom three by the season's close.
They each kept at least as many clean sheets in the final 11 matches as they had done in their opening 27, and four of them kept more.
Importance of clean sheets
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Don Hutchison, who made 220 Premier League appearances for Liverpool, West Ham, Everton and Sunderland, believes that this season Watford could be the team who tighten up at the back in time to rescue their campaign.
"I'm leaning towards Watford because I see a bit of muscle, I see fight in them," he said.
"If you said to me, 'You fast-forward 11 games and someone stayed up because of clean sheets,' I would have thought it would have been Watford."