"The one or two players we'd ear-marked to cause us a threat, we pretty much nullified those guys for the most part of the game."
McPherson said despite not running up the score in the second half he was pleased with how his players kept attacking the Mangere rearguard.
"It was a credit to the players, they are a really focussed bunch of lads and they've shown that all season.
"Maybe the first 10 minutes of the second half Mangere had a little bit of the game but after that we pretty much dominated things again and we could have had one or two more."
After both sides created scoring chances in the early going it was Mozr's seventh minute piece of invention which set the hosts on their way - the Suburbs' player volleying in from a ridiculously wide angle; nearer the touchline than the goal frame, to the joy of the big home crowd.
From there it was all Suburbs as McPherson's team went 2-0 up just after the 20 minute mark, Bryant's header from close range finding the back of the net.
Six minutes later Barnes lashed in a powerful drive from inside the area which Mangere United 'keeper Igor Gjorgievski could only touch into his own net at full stretch.
Facing a 3-0 deficit, Mangere picked up the pace in the opening period of the second stanza but despite spending more time in possession in the Suburbs' half, regular chances were still hard to come by and when Bryant stabbed home in the aftermath of a corner on the hour, there was no way back for the south Aucklanders.
Mangere United coach Miroslav Nikolic said despite the result his side were content with their effort and proud of the run they put together to reach the last four.
"We tried to play good football and the players are quite happy with their own performance," Nikolic said.
"[We're a] division below and it's a different standard but we played up to our standard."
"It's been a great journey and a great experience for the club and people around the club are very proud of what we've done in the last few weeks."
The second ASB Chatham Cup semi-final is on Sunday as Birkenhead United AFC clash with Napier City Rovers at Shepherds Park in Birkenhead (1pm).
Eastern Suburbs AFC 4-0 Mangere United (half: 3-0)
EAS: Rudi Mozr 7', Michael Bryant 22', 60', Brandon Barnes 28'