Non-league Eastleigh will have to do battle with Bolton again after Darren Pratley's last-gasp leveller saved the Sky Bet Championship side's blushes at the Silverlake Stadium.
The up-and-coming Hampshire side's first third-round tie looked set to bring with it a famous giant-killing against the embattled visitors after Dorian Dervite turned the ball into his own goal in the 51st minute.
However, Bolton secured a replay three minutes from time after Pratley netted a scrappy leveller on a bog of a pitch.
It was so bad that the game itself was in serious doubt, with referee Iain Williamson only giving the green light for the match to go ahead 90 minutes before kick-off.
The rain continued on the already sodden pitch and it was Eastleigh who started the game brightly, with Yemi Odubade and top goalscorer James Constable having the best chances in the opening half an hour.
Spitfires striker Odubade was looking the most dangerous player on the pitch but had to be taken off with a hamstring injury, leading Kaid Mohamed to come on in the 35th minute, just days after arriving from Bath.
Bolton, who are bottom of the Championship, started to come into their own as the first half came to a close, but Eastleigh goalkeeper Ross Flitney was on fine form to deny Wellington Silva and Dean Moxey.
The hosts, showing the confidence of a side without a defeat since November, came out strongly after half-time and it did not take long for Jai Reason to unlock Neil Lennon's side.
The winger's dangerous cross sent the majority of the club-record 5,025 crowd wild as Bolton defender Dervite could only inadvertently direct the ball into the back of his own net.
That own goal seemed to wake Bolton up and they began to play more like a second-tier team, but Eastleigh were still pressing at the other end and would have scored a second had Ben Amos not provided a crucial save to deny Constable.
Bolton were struggling on the carved-up pitch and the Vanarama National League side had another chance after t he referee called for a controversial free-kick inside the Bolton box.
Amos picked up the ball after captain Pratley's attempted clearance saw the ball get stuck in the mud, but the Spitfires could not capitalise.
The home side began to tire as the game came to a close and the Trotters finally found the found the back of the net three minutes from time, with Pratley's header finding the net during a penalty-box melee.
Bolton came close to sneaking an injury-time winner as a corner from Silva went just wide of the post, but Eastleigh - the only non-league side to reach the third round - were not to be denied a replay at the Macron Stadium.