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The five-time champion almost recorded a maximum break in the first frame, potting 13 reds and blacks, but suffered discomfort four frames later.
By playing without shoes he broke the dress code, before borrowing some from tournament director Mike Ganley.
The Rocket pounced on errors to build a lead with the resumption on Wednesday.
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It is not the first time O'Sullivan has had to consider his footwear in a tournament, having played December's UK Championship in soft shoes after breaking his ankle while running.
This time around a fan was given the discarded pair but while O'Sullivan continued to dominate, he could not match his standard set in the opening frame, when he even asked officials what the prize money was for a maximum on his way to a 104.
The world number two was twice fortunate to see his opponent miss routine blacks, one to level at 2-2 and another to extend a break of 55 which could have seen the score move to 5-3.
Instead, world number 81 Steadman found himself 6-2 down and contributions of 54 and 75 extended O'Sullivan's lead to five frames.
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Elsewhere, two-time finalist Ali Carter progressed to a second-round meeting with Neil Robertson with a 10-5 win over Scotland's Alan McManus.
Carter, who got the all-clear from cancer for a second time in December, said: "I've been working hard on my fitness and the practice table.
"Peter Ebdon is here to help me on the practice table. All things considered, today will bring me on leaps and bounds and I'm here to win this tournament."
Ronnie O'Sullivan risked a fine by briefly playing in his socks as he took a 7-2 lead in his World Championship opener with qualifier Craig Steadman.