The Lions completed a double-winning weekend at home to move to 11-2 andÂ end the Sharks' eight-game winning streak in the league.
LondonÂ recovered from a slow start to move ahead in the fourth quarter.
But the hot shooting of Dirk Williams kept the Sharks in contention and his late three forced overtime.
However, from 82-82, the home side put together a closing 10-0 run to take the win.
The Sharks gave up a total of 21 turnovers allowing their opponents 27 points including some key scores in the extra period.
There was another double-double on the weekend for Ladarius Tabb after posting 24 points and 14 rebounds, while Justin Robinson just missed out after handing out nine assists to go with 22 points and Paul Guede had 13 with a huge three and defensive steal in overtime.
Leading scorers -Â Ladarius Tabb 24, Justin Robinson 22, Paul Guede 13 (Lions) - Dirk Williams 30, Chris Alexander 17, Leslee Smith 14 (Sharks).
Meanwhile, Cheshire saw off Surrey Scorchers 93-74 as CJ Gettys netted 20 points, while Plymouth battled past London City Royals for an 84-77 victory behind Joonas Jarvelainen's 24 points.
Glasgow overcame Manchester Giants as Ali Fraser posted 23 points, nine rebounds and six assists in a 76-83 triumph on the road.