Queens Park Rangers have admitted to holding an interest in former Aston Villa defender Richard Dunne.
The Republic of Ireland international is available as a free agent after departing Villa Park.
QPR are in the market for an experienced centre-half, having offloaded Chris Samba back to Anzhi Makhachkala.
Dunne would fit the bill, as Harry Redknapp prepares his side for life in the Championship.
No deal has been agreed as yet, but QPR chief executive Phil Beard admits there is a desire on their part to bring the 33-year-old on board.
He said in the Fulham Chronicle: "He's not signed yet but he's a player that Harry would like to bring to the club.
"We're looking at a number of players. The main thing is that they want to play for the club and are ready for the Championship, which is very different to the Premier League."
Celtic kick off their European campaign in Belfast on Wednesday night, less than eight weeks after closing their season with a William Hill Scottish Cup final victory over Hibernian.
Lennon's preparations have been far from ideal - Celtic conceded 12 goals as they lost all four of their friendlies during a stint in Germany.
The former Northern Ireland captain has seen midfielder Victor Wanyama leave for Southampton and fears striker Gary Hooper, who has been struggling with a groin problem, has played his last game for the club as he seeks to join the Kenyan in England.
Nigeria defender Efe Ambrose will miss the clash on the artificial surface at Cliftonville's Solitude ground after being given extra time off following the Confederations Cup.
Welsh pair Joe Ledley and Adam Matthews are expected to miss out through injury while trialist defender Steven Mouyokolo has still to sign a contract, and the likes of Scott Brown, James Forrest, Charlie Mulgrew and new signing Virgil van Dijk have all missed part of the friendly action through injury.
Lennon has already raised the prospect of facing extra-time against Cliftonville at Celtic Park in the second leg and he admits they will need to dig deep against the Danske Bank Premiership champions.
Lennon told Celtic TV: "It's so early, it's a harsh reality of where we are.
"We won the cup final at the end of May and we are back in on the 24th of June.
"It's been staggered and a bit disjointed because we have had a lot of injuries as well.
"Matthews, Ledley, Twardzik and Hooper have hardly featured and obviously we have lost Victor.
"They are the ups and downs you have to cope with during pre-season but I don't think you'll see us anywhere near our best for another two weeks or so."
Celtic closed their German trip with a 3-0 defeat against second-tier side Union Berlin on Friday night and are back at Lennoxtown on Monday before flying to Belfast the day after.
"The trip has been about fitness," Lennon said. "The results have been disappointing but the real work starts Monday."
Meanwhile, Wanyama thanked everyone at Celtic as he departed Glasgow to begin his new career at Southampton following his Â£12.5million move.
The 22-year-old told Sky Sports News: "Celtic have been good to me and the fans have been great. To be honest it was hard leaving them, but I wish them all the best.
"I had a good time with them. I want to thank them for the time I was there. They were really good to me and hopefully one day we will be back.
"I think Celtic have played a big part in my improvement and I just thank the manager and the players. It was really good and I enjoyed playing for Celtic."
And, while he is loath to make predictions about how that will affect their form when the campaign starts, he has been encouraged by all facets of their approach.
Rangers secured their third friendly win this summer when they beat Bristol City thanks to Lewis MacLeod's solitary goal yesterday, with most of their seven summer signings taking part before the squad flew to Germany for a training camp.
Last year McCoist's men were hampered by a signing embargo and an inability to play official friendlies before provisionally securing Scottish Football Association membership less than 48 hours before facing Brechin in their domestic opener.
McCoist, whose side were criticised for their fitness levels on their way to the Third Division title, told the club's official website: "Last year everyone was just thrown in together with no real organisation, no games and certainly not the training schedule we'd have wanted for them.
"This time it is very different and everyone is getting to know each other. We're still in the early stages but everyone is benefiting from the way things are going.
"I'm not going to tempt fate in terms of results but, looking at our preparations, it's like night and day between last summer and now.
"We're miles ahead of where we were going into the season last July and you can see that.
"Our fitness levels are far greater and I'm really pleased with how things are going."
McCoist is hoping to tie up a deal for trialist Bilel Mohsni while the club are also looking to secure Bosnia centre-back Boris Pandza.
But he feels his young players are already responding well to the increased competition.
"Lewis is standing out and Kyle Hutton is doing some top-drawer stuff at the moment," he said.