After dominating possession for long spells of a tentative encounter at the Georgios Karaiskakis stadium, Torosidis broke Latvia's resistance when he netted with a clinical finish following a neat exchange of passes with Kostas Katsouranis.
Victory moved Greece level with Georgia on five points at the top of the section, with Croatia and Israel meeting on Saturday.
Greece captain Georgios Karagounis, making his 100th international appearance, was the first to try his luck in the 10th minute but his speculative shot effort comfortably cleared the crossbar.
Kostas Mitrouglou, leading the hosts' attack, registered their first effort on target five minutes later with a glancing header which Andris Vanins tipped over the bar.
Latvia frustrated their hosts with some disciplined organisation, restricting Greece to long range strikes for the remainder of the half. Midfielder Sotiris Ninis and defender Vasilis Torosidis had efforts beaten away by the resilient Vanins.
The visitors could have gone in ahead when Maris Verpakovskis broke clear in the 44th minute following a defensive mix-up, but the striker took one touch too many and Greek left-back Georgios Tzavellas was able to make a crucial recovering tackle.
Greece made the breakthrough after 58 minutes when Torosidis surged down the right flank before playing a neat one-two with Katsouranis and then slotting the ball past Vanins into the left corner.
