One 750-ml bottle sparkling wine, such as Spanish cava, chilled
Fresh pineapple chunks, for garnish
In a large pitcher, combine the lime juice and sugar and stir briskly until the sugar is dissolved. Add the rum, orange liqueur and grenadine and chill the rum mixture for about 1 hour. Just before serving, add the sparkling wine and pineapple chunks and serve in punch glasses.
The rum mixture can be refrigerated overnight. Stir in the sparkling wine and pineapple chunks just before serving.