Crews working to seal BP's damaged well in the Gulf of Mexico have to carry out one more pressure test before declaring the well permanently sealed, officials have said.
The test is on the cement seal completed on Friday.
The well's closure will bring to an end a nearly five-month battle for BP after a rig exploded in April, killing 11 people and causing a massive oil spill.
No oil has spilled since a temporary cap was placed on the well in mid-July.
Once the pressure test is complete and officials are confident the seal will hold permanently, the well will be declared "dead", Rich Robson, the offshore installation manager on the Development Driller III vessel, is quoted as saying by the Associated Press news agency.
The 74 barrels of cement pumped in on Friday have dried, he added.
The pressure test is expected to happen late on Saturday.
Engineers will exert 15,000lb (6,800kg) of pressure against the cement plug to make sure it will stay in place.
The cementing operation began on Friday, a day after a relief well finally intersected the damaged one.
BP said earlier that when cementing is finished, the relief well would also be plugged and sealed.
Clean up
This final sealing will mean BP can leave the site and concentrate on dealing with the aftermath of the spill.
At the beginning of August, the US government announced that almost three-quarters of the oil spilled in the Gulf of Mexico had been cleaned up or broken down by natural forces.
The remaining quarter was thought to be "degrading quickly".
But more recent research noted an undersea plume of crude oil-based chemicals up to 200m high and 2km wide, extending 35km from the spill site.
Despite optimism about the clean-up, the damage to the local economy, wildlife and the ecosystem of the Gulf is hard to fully assess yet.
