Newcastle United manager Alan Pardew has claimed that it is "impossible" for Chelsea to remain unbeaten across four competitions throughout the season.
The table-topping Blues have not lost any of their first 21 domestic or European games this campaign ahead of Saturday's Premier League trip to Newcastle.
However, Pardew feels that it is inevitable that Jose Mourinho's men will slip up somewhere.
"I think it's difficult - obviously Arsenal have done it and Chelsea have come pretty close before," he told reporters.
"But not in all competitions - that is impossible and I think Jose has admitted that. But they're making a very good job of it at the moment.
"It's the best Chelsea team that I've ever seen and I've watched them since I was about 12 so I know them pretty well. I think Jose is pretty pleased with what he's got."
Chelsea have lost to the Magpies on each of their last two top-flight visits to St James' Park.
Joe Fish
