Sean Lineen has warned his absent Scotland players that they face a battle for places after Glasgow Warriors lost 23-22 to Sale Sharks.
Glasgow were without several internationals through injury against the English visitors.
And the Warriors coach sent on his academy players for the second half of the pre-season friendly at Firhill.
"These boys take the bull by the horns and make it hard for those guys when they come back," said Lineen.
"We scored four cracking tries. Each one was well-crafted and we have worked really hard on that in pre-season, playing the game at a high tempo and I am really happy from that point of view."
Despite Glasgow scoring one more try than Sale, it was the English side who came from behind for a deserved win.

Firhill is a hard place to win and Glasgow are a good side
Sale Sharks head coach Mike Brewer
However, Lineen told BBC Scotland: "You don't win points in pre-season, we have to blood the players."
The coach highlighted Richie Gray, Stevie Swindell, Freddie Aramburu and Duncan Weir for their contribution.
Weir shared the fly-half post with Ruaridh Jackson as Glasgow look to fill the void created by Scotland international Dan Parks' move to Cardiff.
"Duncan Weir - what an outstanding prospect, the way he controlled the game - he can kick the ball," Lineen said of the player signed from Glasgow Hawks.
Another summer signing, Henry Pyrgos, who joined from Loughborough University, also impressed at scrum-half in the absence of injured Scotland captain Chris Cusiter.
And the 20-year-old said: "It was really nice to get my first game out of the way.
"I've never played at this level before and you notice the pace and the physicality is a lot different and it is a big step up for me.
"After 20 minutes, I was really tired. Beforehand, I was really nervous to get the first few passes out of the way to make sure they go in the right direction.
"After that, you relax and it is just another game of rugby. The few senior boys that are in the side definitely helped beforehand.
"I felt that we were on the front foot a lot of the time and we were not under that much pressure."
Sale coach Mike Brewer was pleased with the performance of his own side, which was minus England internationals who had been given a longer summer break.
"First win and first game on UK soil, so it was a good run-out for both sides," said the former Scotland forwards coach who took over at Sale in April.
"Sean will have learned a lot and I have as well - that, if we don't hold on to the ball against teams like Glasgow, they will punish you for it.
"Other than the kick-off, we did not hold on to the ball for more than two phases in the first half.
"Firhill is a hard place to win and Glasgow are a good side."

This article was posted on 21-Aug-2010, 06:37 by Hugh Barrow.