MILAN — The Celtics return to normalcy Tuesday, back in Boston after their European journey. They have three more weeks to prepare for their season-opening showdown with the Miami Heat.

That preparation was made more important by a rather distasteful loss to Fenerbahce Ulker Friday in Istanbul, a 97-91 defeat that exposed the fact that even though the Celtics are laden with talent, if they are lackadaisical or lack focus they will be out-executed.