The 23-year-old had been having a tough night in the shooting circle but had an opportunity to close the gap to one with her side having the next centre pass.
But she lost her footing and twisted her left knee. She had to be stretchered off the court.
It is unclear how bad the injury is but it looked serious. The Steel has already lost back-up shooter Georgia Heffernan for the season to a knee injury.
If O’Connell is gone for the campaign as well, that would be two shooters ruled out in two weeks.
When the match resumed, the Pulse had possession and closed out the game to win 40-37.
The defending champion was perhaps a little lucky to keep its record intact.
The Steel midcourt trio of Shannon Saunders, Gina Crampton and Kate Heffernan kept their side in the match with some brilliant reads and crafty work.
Saunders, in particular, snaffled some crucial turnovers.
Steel coach Reinga Bloxham could not be reached for comment but co-captain Te Huinga Reo Selby-Rickit told the Sky Sport commentary team it was an improved effort from her side.
"All we asked is that we improve every week and I think we’ve done that," she said.
"The Pulse are a good team and, even though we know we could have won and we had the opportunities to win. We are happy with the improvement and the bonus point."
Steel defender Taneisha Fifita made a bright start, picking off an early errant pass from the Pulse.
But it was Saunders who stood out. She used her court craft to cut off several passes, and the long-limbed Kate Heffernan made a nice read to secure a steal as well.
The Steel had to work double time to get the ball to its shooters, though. The Pulse defence proved really difficult to break down.
O’Connell was shaky under the net but her side still went into the break 12-11 ahead.
The Pulse shot a perfect game in the previous encounter between the teams but finally missed a shot in the second quarter.
Ameliaranne Ekenasio put up the rare miss. But the Pulse had still edged ahead by two at halftime.
Defender Kelly Jury used her reach to upset the Steel shooters and that helped make a difference.
Goal attack Kalifa McCollin struggled to get the ball up and over and into the net. She landed just one from four in the period.
The Steel scrapped hard but the misses were starting to stack up.
The Pulse stretched out to a 27-22 lead courtesy of those oopsies in the shooting circle.
The Steel needed to mount a run but ran into some really tenacious defence.
It trailed by four goals with a quarter remaining. It was not an insurmountable margin and the Steel secured enough turnover ball to win the game.
Had O’Connell not slipped, the result was still hanging in the balance.
ANZ Premiership
