The exasperated cries of the Honduran's name from his boss, who bounced, yelled and gesticulated for the duration of the game, rang out more than once from the away dugout.
To be fair to the wing-back, he was in good company.
Neil Lennon did not miss any of his players on Saturday afternoon as he patrolled the technical area in Paisley with an energy and urgency that showed just how much he wanted the result, venting to those in front of him – and those behind him.
There have been suggestions that Celtic are now on cruise control as they coast their way to a second successive title.
Accusations of complacency due to the whopping lead they carry in the SPL were thrown in the aftermath of their defeat to Motherwell last week.
Lennon, though, dismissed those suggestions on Saturday with a performance all of his own that was as riveting and entertaining as anything the on-field contest could offer.
Had Celtic found themselves out on their backsides on Saturday, it would have been the end of their season. And Lennon knew it.
The league is as good as over, the European campaign has all but vanished and a coveted treble has gone.
The Hoops need the focal point of the Scottish Cup final so that they have an aim and a purpose over these coming months.
And Lennon was as pumped up for the occasion as he would have been had his side been playing the cream of European opposition for the biggest prize that football has to offer in the Champions League.
Izaguirre incurred his wrath on too many occasions to document. The defender, culpable last week at Fir Park, was involved in another mix-up against St Mirren that led to the Saints levelling the game.
It was, ultimately, little more than a statistical note, but his uncharacteristic sloppiness was met with a tirade from his manager.
Lennon cut an incongruous character at the weekend. Smart in club suit, shirt and tie, he emerged from the dug-out in the first few seconds of the game to remonstrate and cajole, to plead for more from his players, to mouth off at the fourth official at every 50-50 decision and to take great delight at the bating and sniping from the within-ear-shot crowd behind him when Celtic twice got their noses in front.
Many of his remonstrations were justified; Thomas Rogne looked ill at ease trying to keep an eye on Steven Thompson; Kelvin Wilson ought to have been more commanding; Anthony Stokes did not provide the deadly, killer touch that his manager so desired.
Even James Forrest, who skinned Paul Dummett so often the Saints on-loan left-back looked punch-drunk by the time he left the pitch with seven minutes left, got it in the neck for not seeing Gary Hooper quickly enough for a short corner.
Lennon wanted the win, wanted atonement for the Scottish Communities League Cup defeat, and he got it.
But coping with the black and white stripes of a dogged St Mirren side are one thing; the same colours sported by Juventus on Wednesday night will be another.
And given that Celtic have acquitted themselves with such distinction on the European front this season, they will not want to bow out on a hiding from the Italian champions.
The 3-0 scoreline from the first leg was somewhat harsh on his men, but he will want to show that his side have a bit of pride and still have something about them.
On that front, he still has plenty to think about for the midweek trip to Italy.
Worryingly for the Celtic boss, there was a soft centre about his team at the weekend, just as there was when they played Motherwell last week.
Rogne and Wilson are not the club's best central defensive pairing and there was too much uncertainty on show at the weekend against St Mirren.
Charlie Mulgrew is expected to be fit for the game against Juventus and it is anticipated that he will be welcomed back into the side.
One of the positives for Lennon these past few weeks has been the return to form of Joe Ledley. The midfielder has proved himself to be one of the Hoops' mainstays with performances that tend to be stable, steady and relatively sensible.
They will need as many calm heads as possible as they head to the heat of Turin.