Ibrox side Glasgow Rangers have been on tour of America over pre-season.
Rangers have a number of youngsters on the fringes of their senior line-up, but the Ibrox side’s transfer business has bolstered Warburton’s options in the first-team.
Rangers have already brought in eight new players over the transfer window so far, with more expected to arrive in the coming weeks, meaning that competition for places has been heavily increased.
Rangers have, however, still included a number of their more promising youngsters on their America tour.
Warburton played four of the Light Blues' prospects in their 2-1 friendly victory over Charleston Battery yesterday evening.
And the former Brentford boss said: “The better quality of player we bring in, the harder it is going to be to make that transition from youth player to first-team player. They are aware of that, but Tom [Walsh] came in and did great in well, his two spells, and it’s never easy doing that.
“Jordan [Thompson] came in and did very, very well, Ross [McCrorie] came in and filled Tav’s boots well and young Ryan [Hardie] did well up front too.”
Rangers scored their goals against Charleston through Josh Windass and Harry Forrester.
Rangers are set to travel back to Glasgow tomorrow, as they step up their preparations for the new campaign.