The forward had been out of action since early December with a hamstring injury but snatched an equaliser at St James Park just when it appeared that Ian Evatt’s side had produced another false dawn.
The Bolton boss hoped a new look, including debutant Kieran Lee, would mean better fortunes after a 10-day break, but when poor defending from Ryan Delaney gifted the Grecians an opener, it was nearly game over.
Gnahoua, who had memorably signed for the club because it was local to his home, was electric when he came off the bench to get Wanderers back into the game.
Lee got an early taste of the cut and thrust of League Two football in the opening exchanges, where no player was able to retain possession for more than a fleeting moment and both sides jostled for superiority.
There were nervous moments for Matt Gilks and Delaney early on as Exeter’s mobile front men Matt Jay and Ryan Bowman made their presence known.
Wanderers had been unable to field new signing Declan John, who is nursing a hamstring injury, and it was left to Harry Brockbank to fill in the gap on the left side of defence, with Gethin Jones moving out to the right.
Evatt had hinted that he was about to abandon his trademark three-man defence in favour of a back four but the decision was surely made easier for the Bolton boss by the fact he lost both John and Peter Kioso at the start of the week.
The net result held firm under pressure in the first half, but Wanderers were helped out by the woodwork after Bowman got around Gilks 33 minutes in, his shot bouncing off the post and back into the grateful arms of the keeper.
Bolton had looked susceptible in the wide areas, especially when members of their three-man midfield were pulled out to the touchline to defend.
In that instance it had been Andy Tutte who completely missed his challenge on Joel Randall, whose pass inside then created the opportunity for Bowman.
There were other moments too where Bolton’s defence seemed to creak under the pressure, and Gilks was needed to push a late first-half free-kick over the top from Jay to keep the scores goalless going into the break.
In an attacking sense, the Whites once again played in patches. Lloyd Isgrove looked dangerous running with the ball, when the bobbling surface would allow, but the home defence was only once seriously breached, and that was when Eoin Doyle got free on the right, cutting inside the box to bring a decent save out of Jonny Maxted.
There were brief flutters of football but Exeter had done their homework and definitely restricted the effectiveness of Antoni Sarcevic, well-known to folk in these parts from his time down the road at Plymouth Argyle.
It had felt like an important statement had been made when Bolton jogged back down the tunnel without conceding but the pressure showed no sign of relenting when they emerged back into the Devon drizzle for the second half.
Gilks made another smart stop with his feet after Bowman had helped a bouncing ball on for Randall and Jay had a volley blocked well by Delaney – sparking a furious reaction from Sarcevic, who claimed the Exeter man had used his hand to control the ball. Inevitably, a yellow card followed quickly from referee Sam Allison.
Wanderers started to invite pressure, conceding a handful of free kicks around their own penalty box. And then, almost inevitably, their defences were broken.
At 5ft 8ins, the physical difference between Exeter front man, Jay, and Wanderers’ towering defender Delaney is hard to miss. Not so easy to fathom was how he out-muscled the Irishman on the touchline to hook a cross back into the six-yard box, which bounced awkwardly into the net off Ricardo Santos for the opening goal.
If there was a positive to be taken, it is that Bolton tend to play better once they are behind. And so it proved once more.
Evatt switched his shape a little, bringing on Ali Crawford and Gnahoua for Lee and Nathan Delfouneso, and within a couple of minutes the pair had helped to drag the Whites level.
The goal was right out of Evatt’s fantasy playbook. Seemingly pegged back in their own half, Wanderers broke with clinical precision, Crawford spraying a fine switch-pass out to Sarcevic on the right with his dangerous cross bundled in from inches out by the returning Gnahoua for his second of the season.
Now it was Wanderers’ turn to attack. Sarcevic once again burst into life in the latter stages, sliding another dangerous cross into the six-yard box which frustratingly could not be turned home.
Gnahoua sent a bouncing shot wide of the post with eight minutes left on the clock, the home side by now starting to rock on their heels.
And moments later, the same man popped up again on the left, shifting the ball on to his right foot to arrow another shot inches wide of Maxted’s post.
Both sides knew the next goal would be a knockout blow. Bowman’s cross bounced off Santos and into the hands of Gilks at one end, Isgrove sliced a shot straight at Maxted at the other.
Deep into stoppage time, Wanderers were penned back in their penalty area, defending a succession of long throws and crosses, when home substitute Nigel Atanaga turned an overhead kick on to the crossbar.
Just as it seemed that Bolton had ridden their luck as far as it would go, the final whistle bailed them out.
A hard-earned point indeed – but they might need more if this season is to have the successful conclusion that Evatt craves.
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