Global Motorsport Media
F1 officials late on Friday were working to solve a problem with the Singapore street circuit's kerbs.
Initial practice was delayed as the FIA's Charlie Whiting inspected the temporary kerbs, bolted to the track surface, at some corners.
Germany's Auto Motor und Sport suggested the issue may have been pre-empted by Pirelli following a routine inspection by the official tyre supplier.
Some of the kerbing, another section of which was dislodged when the session resumed, was simply removed for Friday's running.
Asiaone correspondent Tony Ng said the problem "should be fixed by tonight (Saturday)".
"There are some areas where the bolts are coming out of the kerbs -- they must be taking some serious force from the cars," said McLaren's Lewis Hamilton.
I continued driving as though the kerbs were there
The British driver revealed that unlike some of his rivals, he practiced on Friday as though the missing kerbs were still there.
"We don't yet know whether or not the kerbs will be reinstated tonight, so I continued driving as though the kerbs were there," said Hamilton.
"If they're not replaced, then we should gain an extra couple of tenths by being able to run as wide as some of the others did."