The Arsenal winger made six appearances for the Whites in a temporary spell at the end of last season and he returns to find a depleted attack.
Following Jermaine Beckford's departure to Everton, new arrival Billy Paynter was expected to have big shoes to fill from the off after his move from Swindon but the striker is ruled out with a shin injury.
Robert Snodgrass has been sidelined for a month with a knee injury while Max Gradel and Davide Somma are suspended.
Goalkeeper Kasper Schmeichel and centre-back Alex Bruce are expected to make their debuts following summer moves from Notts County and Ipswich respectively.
The other new faces jostling for their Elland Road bow are Paul Connolly, Fede Bessone, Neill Collins and Lloyd Sam.