The victory lifted Palace to 16th in the table, four points above the relegation zone, and Tomkins said Allardyce's emphasis on the defensive side of the game had paid dividends.
"In recent weeks the boss has taken us to one side on the training ground, both as a defensive unit but also as a team group, to work on our shape with a massive emphasis being on clean sheets," Tomkins told the club website.(www.cpfc.co.uk)
Allardyce replaced Alan Pardew in late December and after taking only two points from his first five games, he has managed to build some momentum at the club.
"It is not just about the back four and the 'keeper but also those working from the front, sitting in when needed and then breaking out in numbers on counter attacks when the opportunity comes about in games," added Tomkins.
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"At times before we would (have) tried to chase the game, maybe conceded and then its backs against the wall but now there is a confidence all around the team that we can keep clean sheets."
Palace visit league leaders Chelsea on April 1 before facing Southampton on the road four days later.
(Reporting by Hardik Vyas in Bengaluru; Editing by Peter Rutherford)
