Sunderland can confirm their Premier League status for another year if they beat Everton later this evening.
Watmore has been in excellent form for the Black Cats in recent weeks, with a number of his cameo appearances catching the eye.
However, Allardyce is fearful of putting Watmore in his side’s starting, as he does not want to risk limiting the youngster’s impact.
“It’s a thought. Do we lose the effect of Duncan Watmore if we start him, rather than use him as an impact player?” said Allardyce.
“He’s still a young lad whose learning the game and you wonder if you start him, he can have that impact straightaway.”
Watmore is regarded as one of Sunderland’s brightest youngsters, and he has shown his quality in flashes this season.
The attacker has made 24 appearances in the Premier League this term, but only six of these have been as a starter.
Allardyce may be loathed to throw Watmore in tonight against Everton, as it is such an important match for the Black Cats.
Sunderland will confirm their Premier League safety for another season if they are able to beat the Toffees - relegating both Newcastle United and Norwich City.
If Sunderland fail to win later, they will need to get three points against Watford on the final day to ensure that they remain in the top flight.