Glover teamed up with Heather Stanning in the capital last summer to secure Great Britain's first-ever gold medal in women's rowing, blazing a trail for the likes of Grainger and Anna Watkins to follow.
But Stanning, a Royal Artillery Captain, has since joined back up with her regiment forcing Glover to form a new partnership for the 2013 season.
And in Swann Glover might just have met her match after the duo stormed to gold at the second World Cup of the season at Eton Dorney last weekend.
Grainger was there in person to witness the victory and although it is early days, the Scot is predicting great things for the future.
"Obviously Helen and Heather were the Olympic champions at Dorney and it is very hard to replace someone in a small boat because you are changing 50 per cent of what has gone before," said Grainger, who was in attendance at the Lloyds TSB National School Sports Week.
"It can be very hard to change that and keep it to the high standard that you want it to be but these two seem to show no sign of slowing down and that is testament to both Helen and Polly.
"From Polly’s point of view she seems to fit in very well and she can't let what has gone before get in her way and she just needs to keep her head down and work hard which is what she seems to be doing.
"And Helen wants to make this work too and she is a tremendous athlete and will keep working hard to keep being successful and the two seem to want to make it successful which is great.
"They seem to fit together really well if early results are anything to go by and they have confidence in each other which is half the battle in a small boat.
"Helen will want to hold that high standard high still despite the changes. She has been unbeaten for some time and that is the goal moving forward.
"It is early days but they way they have started they look like being really good together in the pair."