No test cricketer should feel his place in the side is secure.
At least that's the old line. A small group of players, with names like Hadlee, Lara, Tendulkar, Warne, Botham, Richards of recent vintage, would have been well within their rights to assume their positions were rather safer than some of their team.
But as a general rule of thumb it's a pretty decent philosophy in terms of trying to draw the best out of players.
There are New Zealand players down the years, and indeed even now, who have felt safer than they should simply because of a shortage of challengers pressing for a place.
Very few of the New Zealand squad for the two tests against Sri Lanka starting tonight should be feeling too cosy, and perhaps the player reckoning he needs to perform more than most is Kruger van Wyk.
Being New Zealand's test wicketkeeper has been a precarious business since Brendon McCullum decided two and a half years ago that he wanted to be a specialist batsman and hung up the test gloves.
Auckland captain Gareth Hopkins played four tests - one was in England four years ago, when McCullum had a back injury, plus the series in India later in 2010 - before being shunted aside. His batting average was 11.83, albeit in demanding circumstances.
Reece Young was then given a chance last year. He had five tests against Pakistan, Zimbabwe and Australia, averaged 24.14 before being abruptly cast aside, albeit after an average series across the Tasman.
And so van Wyk got his chance in Dunedin against South Africa, land of his birth, last March.
He got a lucky break, in that BJ Watling was to don the gloves and add to his eight tests - only one of which was as a specialist wicketkeeper, when he hit a century against Zimbabwe last season - only to hurt a hip the morning before the test.
Van Wyk has been the encumbent for the past seven tests. He's averaging 23.07, his latest test, in Bangalore in August, produced a solid double of 71 and 31 and his glovework has been pretty steady.
But the little Central Districts man could be forgiven for looking over his shoulder.
There, he'll find the resurgent Watling, on the back of strong ODI batting form, plus having the keeping job in the 50-over form; and Wellington's Australian transfer Luke Ronchi.
It's not hard to find those willing to pronounce Otago captain Derek de Boorder as the best gloveman going in the domestic game. He snaffled nine catches in the draw at Hamilton this month, averages 38 in first-class cricket and has just turned 27.
Ronchi played seven limited-overs internationals for Australia in the 2008-09 season before being moved on. His game is more suited to the shorter forms. He is eligible for New Zealand from mid-January.
There are interesting times in the keeping department.
National selection manager Kim Littlejohn dropped a broad hint before the squad left for Sri Lanka about his and coach Mike Hesson's thinking. "We're about showing some faith in the players who have done the business for us. The message is about stability in building a team."
That sounds like good news for van Wyk - at least as long as he delivers a strong standard of work. A queue is building behind him.