Smalling: Man Utd have leaders worried
Smalling was on the scoresheet in victory at Hull City on Boxing Day.
"We hope they (other teams) are getting nervous," said Smalling. "We're starting to get on a good run.
"If people are starting to look over their shoulders, we're doing a good job.
"Despite our start, I don't think you can ever write off United because of what they have done over the years. We knew our time would come and hopefully this is the start of a really good second half to the season where we can put the pressure on and move up the table.
"We're in a rich vein of form. It's one of those seasons where there will be a few ups and downs and some teams have yet to have their downs. We have had our blip and can't really afford any more."