Christened the 'Voice of Irish Racing' by his At The Races colleague Matt Chapman, O'Brien is widely regarded as one of the best all-round broadcasters in the game.
Be it in his presenting role for ATR, commentating in the point-to-point fields or, as he will be at Aintree, calling the Grand National for BBC Radio 5 Live, O'Brien is unflappable.
At least he has been to date, anyway, and he has admitted to being quite relieved that being in position three of the four commentators he will at least miss the scramble over the first six fences and, with a dollop of luck, be calling home his pride and joy in a finish.
He will be joined by Martin Harris, Darren Owen and John Hunt on the airwaves.
"I must admit I'm not exactly looking forward to calling my own horse in a National," said O'Brien.
"Although, being the third of the four commentators used at least the race will have thinned out by the time they reach me.
"If I'd been down to do the first six fences I'm not sure how I'd have coped looking for my own horse while trying to tell everyone else how the other 39 are doing!
"Obviously, there's no guarantee at all he'll even get as far as my position but you wouldn't be human if you weren't keeping a little eye on your own horse.
"There are nerves for a National without having a runner so I've no idea how I'll feel come the day. I have actually called one of my own horses before when Bayan ran in a handicap on Irish Champions Weekend in 2014. We lost the pictures so I had to commentate and he finished fourth.
"I felt pleased when an ex-producer pal of mine told me afterwards he'd have had no idea I owned a share in one of the runners, especially one involved in the finish."
Vics Canvas, trained by Dermot McLoughlin, is likely to be among the outsiders come the day and while he may be 13 and no horse his age has won since Sergeant Murphy in 1923, there are pieces of his form that would give him an each-way chance.
He finished second in the Bet365 Gold Cup last season and as recently as November he was beaten less than four lengths into fifth in the Becher Chase to gain the all-important Aintree experience.
"As he's small the better ground helps him with his jumping and it was soft in the Becher yet I still felt he had a chance two out," said O'Brien.
"He just ran a bit keen so he had nothing left for the run-in, but you'd hope in a bigger field he might settle better, though of course that then brings its own dangers with fallers and all sorts of trouble.
"He ran a blinder at Sandown in the Whitbread, too, and that was the last time he raced on nice ground so we're hoping it sparks him back to life."
Empire Of Dirt tops Topham contenders
Empire Of Dirt is among 44 horses standing their ground at the confirmation stage for the Crabbie's Topham Chase at Aintree on Friday.
The Colm Murphy-trained nine-year-old was victorious at Cheltenham in the Brown Advisory & Merriebelle Stable Plate Handicap Chase.
Willie Mullins is mob-handed, having left in Sir Des Champs, Blood Cotil, Turban, Ballycasey and Tennis Cap.
Village Vic is ante-post favourite, having enjoyed a fruitful winter, winning four races on the bounce, including the Caspian Caviar Gold Cup at Cheltenham in December.
However, his successful streak came to an end at the Festival when he was a well-beaten ninth to Vautour when stepped up in class for the Ryanair Chase.
Others in a strong list include Paul Nicholls' Bouvreuil, Venetia Williams' Grand Sefton winner Bennys Mist, David Pipe's La Vaticane and the Nick Gifford-trained Fairy Rath, who was second in this race 12 months ago.
Supreme Novices' Hurdle winner Altior is among 24 entries for the Grade One Top Novices' Hurdle.
Nicky Henderson's charge upset the Mullins hotpot Min at Cheltenham and is likely to face strong opposition from the champion jumps trainer.
Mullins has put in Bello Conti, Bellshill, Bleu Et Rouge, Footpad, Limini, Petit Mouchoir and Yorkhill, while Aidan O'Brien has Slowmotion.
Amongst a strong home team are Nick Williams' Betfair Hurdle victor Agrapart and Alan King's Yanworth.
Willie Mullins makes Melling move with Vautour
Vautour heads a strong Willie Mullins presence in the JLT Melling Chase at Aintree on Friday.
The brilliant Ryanair Chase winner is also entered in the Betfred Bowl on Thursday but is expected to line up in this contest.
Mullins is covering all bases as he has also given the Melling option to Felix Yonger, Un De Sceaux and Vroum Vroum Mag.
Other Irish-trained possibles are Bright New Dawn, Clarcam, Gilgamboa and Smashing.
Completing a 13-strong entry are Al Ferof, God's Own, Saphir Du Rheu, Somersby and Vibrato Valtat.
Thebarrowman carries on winning run
Thebarrowman was made to work hard to keep his unbeaten record intact in the Annual Family Day 15th May (C & G) Maiden Hurdle at Navan.
Successful in a point-to-point and a Fairyhouse bumper, Adrian Keatley's six-year-old was the 1-2 favourite to follow suit on his jumping bow.
He travelled kindly in the lead for Davy Russell but had to fend off Craiganboy between the last two flights before holding off the late lunge of Stand Up And Fight by half a length.
"We may have a look at Punchestown for the three-mile novice."