Despite the troubled club's demotion to the Irn-Bru Third Division, a host of international players have opted to remain at Ibrox - including Little, who agreed a new deal with Ally McCoist's side in the summer despite their fall from grace, while Shiels left Clydesdale Bank Premier League side Kilmarnock to join the Gers.
Whether or not life in the fourth tier of Scottish football will be enough to sustain Little and Shiels through a difficult World Cup qualifying campaign remains to be seen, and O'Neill said: "Everyone asks: 'Will the level they're playing at prepare them to play internationals?' Well, the reality is they've only played a couple of games so we're not really able to assess that at this minute in time."
He added: "We will be able to assess that throughout the season, but certainly both players have looked very sharp.
"Rangers are playing at a lower level competitively but the standard they prepare at will still be the same as they did previously.
"As has already been shown (by the 2-2 draw at Peterhead), Rangers are effectively going to be playing cup ties every week - especially away from home. I don't see it as a huge issue but it's something we'll monitor over time and for future squads.
"It's something that will be an ongoing process."
O'Neill confirmed he had been party to the pair's contract decisions and had not encouraged them to pursue a future away from Rangers.
"All the lads have kept in good contact with me in relation to their club situation," he said. "It is important to me that they're happy at their clubs and playing at the highest level possible and I spoke to both Dean and Andy before they made their decisions.
"But it would be unfair of me as their international manager to say: 'If you sign there you won't get picked'. They make their living through their clubs, not through me and that's a situation you have to appreciate."
Source: PA
Source: PA