Claude Puel insists he is under "no obligation" to play big-money short-term signing Martin Caceres.
Saints signed free agent Caceres to plug the defensive gap left by Jose Fonte's January move to West Ham and Virgil Van Dijk's ankle injury.
The 29-year-old is yet to feature though, and could even turn out for the under-23s on Monday rather than face Watford on Saturday.
Caceres has signed a bumper contract until the end of the season but Saints manager Puel remains adamant the ex-Juventus centre back must earn his first-team chance.
"There's no pressure for me, no obligation with any player," said Puel. "Young players, experienced players - all my players are important.
"I try to put my best players on the pitch. For the first team for me it's important to see good things."
Saints face Watford at Vicarage Road on Saturday in a desperately quiet month featuring just two fixtures.
A fter the Christmas feast comes a late-season famine to leave Southampton's French boss Puel frustrated - but still intent on selecting his strongest line-up this weekend.
And if Caceres does not win favour at Watford then Puel admitted he may throw the new arrival into action for the under-23s.
" He improves step by step in every training session," said Puel. "I don't know if he can start the next game; perhaps we can see him with an opportunity to play for the under-23s against Chelsea on Monday.
"It's perhaps a good opportunity for him to play a good official game against the good young players of Chelsea."
While Puel has spent the first half of the campaign rotating his resources, he admitted that will now become more difficult.
"From the start of the season it was important to give people game time," said Puel.
"Now we have two players competing for each place and that's a good thing.
"But of course now it's difficult to keep everyone in a good concentration and a good spirit."