Former Bournemouth defender Stephane Zubar was one of two contract hopefuls given a run-out in defence at Firhill as Archibald looks to add more options to his squad.
Thistle rounded off their pre-season schedule with a 3-1 win over Sunderland as the Jags boss saw his side in action for the final time ahead of their top-flight opener against Ross County next week.
Archibald said: "The trialists done okay. It was a big ask for them - they only came in and trained in the last couple of days.
"The lad in the first half is young and he has a lot of good qualities. We will get a look at them. I am close [to signing someone], but not close enough. I am speaking to someone just now but we will see what happens.
"I am hopeful that he is in for tomorrow but it might not happen, so I can't name any names. He is at another club just now."
Despite Thistle starting brightly against a young Black Cats side, who fielded former £5million man Danny Graham at the head of attack, it was the visitors who took a 15th-minute lead.
Duncan Watmore, the winger who spent the second half of last season on loan at Hibernian, swung in a cross from the right flank and defender Tom Beadling headed beyond Paul Gallacher.
After Ryan Stevenson had a shot saved, Christie Elliott fired wide with only the keeper to beat, but the Englishman then pulled Thistle level with half an hour on the clock, heading home Dale Keenan's cross at the back post.
Archibald made a host of changes at the break in a bid to give his players a run-out before the big kick-off and it was sub Steven Lawless who seemed to have clinched the winner on the hour before Stephen O'Donnell made it 3-1 with a late deflected effort.
Thistle have been drawn away to Morton in the second round of the League Cup, with Archibald's side set to head to Cappielow on August 26 or 27.