The winger spoke on the Que Golazo podcast to give an insight into his experience with our head coach.
"I probably keep in contact with Lampard the most as he is in England," Harrison said. "We were always close when we were in New York and it's nice to see him doing so well with Chelsea."
The Englishman has faced Lampard four times since he became a manager and admitted he tries to play well against him to show how good he is.
"Whenever I play against Frank I always try and prove a point to him although last time I didn't do too well against Chelsea. I'm hoping to redeem myself the next time we play them."
"It's always nice to see where these guys are now because they had the right mentality. Even in New York, they could've taken it as a retirement league as everyone calls it and relaxed a bit.
"They always pushed themselves and that's something I admired about them. They still had the right attitude and mentality to be part of that team so it's no surprise to see them doing well."