Neil Lennon admits he needs urgent reinforcements after seeing Ryan Porteous join his lengthy injury list.

Porteous suffered a recurrence of a knee injury during Wednesday's defeat against Motherwell and Lennon fears the 19-year-old centre-back is set for a lengthy absence.

Lennon is also missing goalkeeper Adam Bogdan, left-back Lewis Stevenson and wingers Martin Boyle and Thomas Agyepong through injury ahead of Sunday's trip to face Ladbrokes Premiership bottom club St Mirren. Midfielder Mark Milligan and striker Jamie Maclaren are on Asian Cup duty with Australia.

The former Celtic boss previously suffered a setback when Efe Ambrose exercised a clause in his contract which allowed him to seek a new club and the loss of Porteous has come as a major jolt.

"He's having a scan and then he's seeing a specialist on Monday so I don't know how severe the injury is yet but it didn't look good after the game on Wednesday night," Lennon said.

"It's just another blow. Coming into this month now we've lost arguably our three best players from the first half of the season in Ryan, Martin Boyle, who is out for the season, and Efe Ambrose.

"So we need to get some players in to bolster what we have because we need an injection of freshness and quality.

"We're down to the bare bones. I have five academy players in the squad of 18. So really I have only 13 senior players at the minute.

"We need to do some work, we need to do some hard work, and we need to get up and running and start challenging for the top six."

Lennon has been focusing on bringing in a new striker but he may now have to bolster his defence as well.

"With Efe being away and with Ryan injured... it will depend on the length of time but it's something we'll have to have a look at," he said.

"A striker is what we're working on, and a wide player as well. We want to bring another two in, minimum, between now and the end of January. I think that's essential.

"I'm hoping we can get somebody in for Sunday. We need someone in for Sunday."