Two goals from Lacazette and Laurent Koscienly were enough to give the gunners three points at home to Chelsea.
Arsenal opened scoring in the 14th minute through French striker Lacazette following a Hector Bellerin assist before captain Laurent Koscienly doubled the lead in the 34th minute thanks to a Sokratis effort.
Chelsea who were favorite to win the match started without midfielder Cesc Febragas who has moved to French side Monaco to join former Arsenal player and now coach Thiery Henry.
Uruguayan midfielder Torreira started in todays fixture unlike that of West Ham where he came in as substitute.
Chelsea’s forward consisted of Willian, Pedro and Hazard but the combination did not harm Arsenal defense as they stood firm in today’s game.
Premier League results
In other results from Saturday’s fixture, Wolves proved too strong for Leicester winning the match 4-3.
Bournemouth who were at home defeated West Ham two goals to nil as ten-man Liverpool secured three crucial points at home against Crystal Palace.
Manchester United recorded its seventh straight win to tie in points with Arsenal as Southampton beat Everton 2-1.
Watford who were at home shared spoils to end goalless at the end of 90 minutes.