MacPhee, who joined Villa in August 2021, has worked under three different head coaches - Dean Smith, Steven Gerrard, and now Emery.
Ahead of their clash with Sunderland, Emery said: “Set-pieces are very important and how the referees manage physical duels.
“Even with the goalkeepers, touch them or not, a foul or not, they are blocking goalkeepers, not just one player but two or three - it is sometimes crazy. It is very difficult for the goalkeepers.
“Through it, they are performing, a lot of teams. It is one way in set-pieces, and to be creative. And Austin is very creative.
“We are speaking a lot about set-pieces and we are trying to get advantages through it and compete through it.
“Sunderland is especially one team very good through set-pieces and they threaten the opponent through it. We must defend fantastically on Sunday and we must threaten them.
“How we control the game in 90 minutes, maybe we can stop conceding throw-ins or corners from them. Then, we can exploit it ourselves.”