Grewcock, who has just turned 34, made a try-scoring debut in Buenos Aires back in 1997 when England lost 33-13 in a bruising encounter and is hoping for a more positive outcome on Saturday.
Grewcock said: "That was a special day even though we lost. But I find it very surprising that I'm now in the top 10. The last thing I thought was that I'd get a cap to start with because it was tied in with a Lions tour and there were also a lot of injuries.
"But I'm very pleased to get as many as 66. I'm seriously surprised I've managed to do that. A lot of luck has been in my favour because there have been so many good second rows for England."
Grewcock, who was far from his best in England's 41-20 defeat against New Zealand, goes into the game as the man England are looking to for the fire and drive which has been missing since the days of Martin Johnson.
Defeat against Argentina would be England's seventh in a row and would see them equal the worst losing run in their history.
Grewcock, however, insists that sobering statistic has not played on the players' minds this week as they trained at their Bisham headquarters.
He said: "Whether we have lost four, five or six everybody wants to win that next game, that never changes. It's down to the individuals.
"If we do our jobs properly the points will come and the results will come. Things have got to improve drastically.
"It was disappointing against New Zealand, too many missed opportunities.
"A few bits of my game were disappointing. My defensive line-out work wasn't up to scratch. It was poor, so was our breakdown work. We also need to be more efficient in our ball-carrying.
"That was frustrating but they are things we have worked on and looked to improve this week.
"But against the All Blacks there were also some pleasing parts to our game."