  Li abundances for 9 Turnoff (TO) stars of the intermediate metallicity
cluster ([Fe/H]=-1.4) NGC6752 are presented. The cluster is known to show
abundance anomalies and anticorrelations observed in both evolved and main
sequence stars. We find that Li abundance anticorrelates with Na (and N) and
correlates with O in these Turn-Off stars. For the first time we observe Pop II
hot dwarfs systematically departing from the Spite plateau. The observed
anticorrelations are in qualitative agreement with what is expected if the
original gas were contaminated by Intermediate Mass AGB - processed material.
However, a quantitative comparison shows that none of the existing models can
reproduce all the observations at once. The very large amount of processed gas
present in the cluster does not imply a 'pollution', but rather that the whole
protocluster cloud was enriched by a previous generation of stars. We finally
note that the different abundance patterns in NGC 6397 and NGC 6752 imply
different ejecta of the preenrichment composition for the two clusters.
