Tim Oscroft, BBC Sport
The season just keeps getting better for Brighton and especially for Pedro, the 22-year-old forward that manager Roberto de Zerbi admitted he knew nothing about when he joined after two and a half years with Watford.
He has now scored 10 times from the penalty spot this season - more than anyone in the top five leagues in Europe - and showed a cool head when facing United debutant Ivo Grbic from 12 yards at Bramall Lane.
Pedro sent the Croatian, recently signed from Atletico Madrid, the wrong way on each occasion when opting to go first to his right and then to his left.
And his hat-trick was clinched when he took just enough time to control a pass from James McAtee on the edge of the area before shooting low past Grbic into the bottom corner.
Brighton were untroubled after they had gone back into a two-goal lead and Welbeck underlined their dominance when he shot underneath Grbic from a tight angle deep into stoppage time at the end of the match.
Seventh in the Premier League with more FA Cup and Europa League ties to follow, Brighton seem to have a lot to be excited about in the second half of the season.