United boss Jose Mourinho discussed the team news with BT Sport ahead of the match:
Sanchez last started a Premier League match for the Red Devils in September. He has found himself struggling for form this season, having contributed just one goal and an assist in eight appearances in all competitions.
As such, minutes on the pitch have been hard to come by for the Chile international in recent weeks.
Lukaku, who has returned four goals in 14 matches, has not been in much better form, though Mourinho did start him on the bench for United's most recent match as they beat Everton 2-1.
With the Belgian absent entirely at the Vitality Stadium, Sanchez has the chance to stake a claim for more opportunities.
He will need to perform much better than he has this season, though, or he will find himself out of the team once again when Lukaku is fit.