PARIS, May 13 : Paris St Germain were forced to perform a balancing act to seal their fifth consecutive Ligue 1 title, after spending much of the season caught between Champions League ambitions and an unexpectedly stubborn domestic challenge from Lens. Luis Enrique's side clinched the league title on Wednesday against the team that had been breathing down their necks, as Lens' challenge ended in a 2-0 defeat after months of relentless pursuit. The season became an exercise in careful energy