Bielsa's Whites slipped to a 2-1 reverse in December's Premier League clash against the Hammers at Elland Road in which Tomas Soucek and Angelo Ogbonna both netted from set pieces.
The defeat left Leeds 14th having conceded seven goals from set pieces excluding penalties in their first 12 games but comparatively the Whites have only leaked in five more from corners or free-kicks in their next 14 fixtures and now sit 11th.
The statistics suggest improvement though Bielsa says the proof will be in the pudding against a Hammers side who themselves have now shot up to sixth place, putting themselves in contention for a Champions League place.
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"It is better for a team to show that they have evolved before affirming," said Bielsa, asked if Leeds had learned lessons from the first Hammers clash and were now better at defending set pieces.
The Whites head coach also said there was no 'secret' to West Ham s recent success which Bielsa insists is based on a strong team of players getting good minutes under boss David Moyes.
"A secret or something special I don’t observe," said Bielsa.
"They’ve been able to maintain a stable partnership in midfield. They are two players who are very important. For each of the attacking positions, they have two players.
"Especially with the two wingers and offensive midfielder. The four full-backs they possess are important players. Apart from that, they have resolved the absence of (Arthur) Masuaku.
"Their two goalkeepers have shone and the centre-backs, not only have they been sure at the back, they have also contributed goals in attack.
"They have a very good set-piece taker with his left foot and the manager has been able to obtain some very good minutes of football with that team."
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Thank you Laura Collins