Chesterfield booked a trip to Championship Watford in the third round of the FA Cup with a 1-0 win over Leyton Orient at the SMH Group Stadium.

The National League leaders, who beat Portsmouth in the first round, claimed another League One scalp thanks to a goal seven minutes before half-time when a cross by Ollie Banks deflected off the top of Orient captain Idris El Mizouni’s head into the top corner.

Will Grigg had the first effort on target for the hosts when his close-range back heel at a corner was held by Orient keeper Sol Brynn.

Orient full-back Tom James tested Ryan Boot with a shot from outside the area as the visitors looked to grab the initiative.

It was Chesterfield who struck first when, with 38 minutes gone, a cross from Banks was deflected off the top of the head of El Mizouni and over Brynn.

The Orient midfielder almost made amends after 53 minutes when his shot forced Jamie Grimes into a hacked clearance which spun back wide of his own goal.

Armando Dobra’s deflected shot fell to Brynn and James Berry shot wide as Chesterfield added Orient to their impressive win over League One leaders Portsmouth.