Russell Slade's men climbed back to the summit on Saturday with a 3-1 victory at Swindon that was marred by an attack on goalkeeper Jamie Jones by a fan from who came on to the pitch from the home end.
The Orient boss has called for the supporter to be banned for life, but Slade's focus will now turn to rediscovering his side's consistency after two defeats in their last five.
Bristol City have just two wins from their opening 17 fixtures and will be looking to ease relegation concerns with three points on Tuesday.
Wolves, whose goalless draw with Brentford allowed Orient to go top, are at home to Tranmere Rovers, who secured a 5-1 victory at Coventry City in the shock result of the latest round of fixtures.
Kenny Jackett's men are eight points clear of third-placed Peterborough United and will be keen to extend the gap between the automatic promotion spots and the chasing pack.
Peterborough are on a four-game losing run in League One and without a win in five ahead of their trip to fourth-placed Brentford, who will fancy their chances of leapfrogging the London Road club having gone six unbeaten.
Preston North End will be looking to make it seven games without defeat when they head to Port Vale, while Bradford City will feel confident of staying in the top six as they host basement club Notts County.
Crewe Alexandra are currently four points adrift of safety and will want to chip away at that deficit when they travel to Carlisle United, and Sheffield United could climb out of the relegation zone with victory against Walsall.
Elsewhere in the third tier, Colchester United, who have just one win in their last 17 matches in all competitions, host MK Dons, Coventry meet Rotherham United and Stevenage aim to pull themselves away from the drop zone at Gillingham.
The remaining two fixtures on Tuesday night, Shrewsbury Town face Oldham Athletic and Crawley Town welcome Swindon.
