The Saints manager was critical of his side's second-half performance in the 3-0 defeat at Queen's Park Rangers on Saturday, but knows that victory against a despondent Leeds side could yet prove the catalyst to Southampton remaining in the top division.
"The QPR defeat only makes me more determined; I only hope it will have the same effect on the players," said Merrington, whose side could move five points clear of the relegation zone.
Another defeat (they have won only once away from home in the League all season) would leave morale desperately low going into Easter, with games against Blackburn Rovers and Aston Villa. Southampton then play Manchester United at home and Newcastle away before the 10-day break caused by England's international against Croatia at Wembley.
"We were second best in all departments on Saturday but the players know how I feel and I hope they have had a good hard look at themselves and asked if they could have done more," Merrington said. "I know I will be working even harder now. It makes me dig deep as a professional and I need the same response from the team."
Matthew Le Tissier returns after suspension and Southampton could have the additional fillip of Richard Hall back in defence after a calf injury ruled him out for the last two games. There may also be a recall for Mark Walters. Merrington added: "Every game now will have an effect on the overall picture and we must get something out of it."
John Lukic, the Leeds United goalkeeper, has recovered from the concussion which saw him substituted at half-time in the home defeat against Middlesbrough, a result which left the Yorkshire club with four points from a possible 24 - one fewer than Southampton. Tony Yeboah and Tomas Brolin remain doubtful with a knee injury and a virus, respectively, while Tony Dorigo is unlikely to be risked after a month on the sidelines with hamstring trouble.
Nigel Worthington is unlikely to to be selected with a similar problem suffered playing for Northern Ireland last week, so Lucas Radebe stands by.
"We need to relax a bit more, play with a freshness and improve on recent results. There were signs against Middlesbrough that things were on the mend," the Leeds manager, Howard Wilkinson, said.
n Jo Bonfrere, the Nigeria manager, has walked out on his job and returned to his native Netherlands. The Nigerian Football Federation secretary, Sani Toro, said Bonfrere had left without warning, merely leaving a letter complaining of "indecent treatment and interference in his job". Bonfrere said he would not return to Nigeria until there was a positive response from the federation to his complaints.
The manager, who replaced Carlos Alberto Torres last August, had disagreed with Nigeria's withdrawal from the African Nations' Cup in South Africa on security grounds earlier this year.