The pair, who both seem certain to sign for the Cappielow club, were given around an hour each and were joined by a trio of trialists as Kenny Shiels steps up his search for players to bolster his squad.
Former Wigan right-back Jamie McCormack and ex-Chelsea and Brighton left-back Ben Sampayo, right, both 21, were given run-outs, as was an unnamed striker currently plying his trade in junior football.
A fourth player, 19-year-old Brad Gascoigne, who can play in the centre of defence or midfield, also featured and was later confirmed as having signed for Morton by current club Corby Town.
However, Shiels insisted that a decision on a deal had not yet been made when contacted by the Tele last night.
He said: “We played St Mirren at Parklea and it was a good game. I wasn’t even interested in the result. It was just designed to have a look at some players.
“We had a few players in and I was happy with what I saw. Garry O’Connor and David Robertson both started.
“Obviously they haven’t played for a while and it’s going to take time to get their match fitness up, but I was pleased.
“I didn’t want to push them too soon. Garry got about an hour and David an hour and 10 minutes approximately.
“We’re trying to move a deal forward for Garry O’Connor but we’re waiting on international clearance and we can’t do anything until we get that.
“We also had some trialists playing: Jamie McCormack from Wigan who was out for a year with a cruciate injury and is just back.
“He’s an athletic right-back and got about 80 minutes.
“We had Ben Sampayo at left-back. He’s English, from Dagenham, and was previously with Chelsea and Brighton.
“Bradley Gascoigne, a centre-mid or centre-back — he can play both positions — is from Nottingham. He played with Derby and Birmingham as a kid.
“I’ll be making a decision on these players over the next few days. There is a bit of deliberation to be done.”
Meanwhile, Shiels rubbished speculation linking him with moves for unattached former Hibs striker Derek Riordan and son Dean, who is currently contracted to Rangers.
He added: “There’s nothing happening with Derek Riordan, not at all.
“I think people have seen that Garry O’Connor’s here and put two and two together and got five.
“My two sons were there at the Hamilton game with Sammy Morrow. They just came to watch the game.
“Sammy was with Hibs and Ross County as a player and is the spitting image of Derek Riordan. Everybody has been asking me what Derek Riordan was doing there — Derek wasn’t there!
“Dean came to watch us play. He had no match and trained in the morning you see. There’s no chance of us signing Dean, not at all.”