Other youngsters to shine for the Scottish side included full-back Stuart Hogg and flanker Chris Fusaro.
While the Warriors' international contingent will return in time for the home clash against Ospreys in three weeks' time, Lineen made it clear his established stars can no longer take their first-team places for granted.
"I'm so proud of the guys tonight. The youngsters have come out and put their hands up and put in some fantastic performances, for instance Chris Fusaro and Stuart Hogg, and Duncan Weir kicking eight from eight.
"Also Tommy Seymour was outstanding on the wing, he really marshalled the defence.
"I'm delighted for the players, particularly as we have turned around from the Treviso match a fortnight ago.
"We now have a short break and when we come back we will be integrating the players who have been away in New Zealand back into the fold.
"Then we're back here for the Ospreys, where there will be so many guys challenging for places."
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