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The Potters, who have finished ninth for the past three seasons, were beaten 4-1 by Crystal Palace on Sunday and are bottom of the table after five games.
"We have ambitions this season and if this run continues any longer we won't be able to achieve them," Hughes said.
"We need to turn this round very quickly. We haven't got going yet."
He added: "We've been ninth in the last three years, and we spoke about being better than that.
"Collectively we need to be better. We can't keep conceding easy goals like the first two."
Stoke failed to win any of their first six games last season but then won five of their next seven.
The former Wales boss was backed by his Palace counterpart Alan Pardew.
Some Eagles fans chanted "you're getting sacked in the morning" at Hughes, something Pardew felt was unjust.
"This is an experienced manager with very, very good players," Pardew said.
"Mark will deal with that. I have no concerns for him because he's terrific. He's having a bit of downtime, but he'll be fine. I have heard those chants against me. I don't think it's right."

Tomasz Nowak, 33, of Kirkcaldy, was involved in a collision with a van on the Perth to Blairgowrie Road at about 16:00 on Sunday.
The crash happened at Old Scone, near Perth Racecourse. Police have appealed for witnesses.
Police Scotland said a report had been submitted to the procurator fiscal.

Ann Barnes said Kent was in a unique position with the UK border and needed its officers now more than ever.
She has written to Home Secretary Theresa May to ask for funding cuts to be deferred for a year.
The government said it was taking steps to ensure law enforcement and security agencies had the resources they need.
On Monday, Mrs May said security would be "intensified" at UK borders.
Mrs Barnes said Kent was the gateway to Europe with ports, the Channel Tunnel, tunnels and bridges to the capital, and Dungeness nuclear power station.
The police force acted as the "guardians of our borders" with 35m people travelling through the county each year via ports and the Channel Tunnel, she added.
She said most were ordinary people but some were hostile, bringing in weapons or terrorist materials, and Kent needed to make sure resources were available.
The force had already lost 500 officers and 720 staff under Â£60m cuts already imposed, and another Â£61m cuts could come as the police service looked at between 25% to 40% cuts over the next four years, Mrs Barnes added.
Police minister Mike Penning said the government had undertaken significant work to strengthen its response to the threat from terrorism and had protected the counter-terrorism policing budget.
He said counter-terrorism spending across government would continue to be protected in the current spending review.
"Decisions on wider police funding will not be made until the spending review reports and the operational deployment of resources is a matter for chief constables and police and crime commissioners," he added.
The government said the Border Force worked closely with the police and National Crime Agency to prevent importation of weapons and identifying suspects.
Stoke City boss Mark Hughes says his team's poor start in the Premier League could see them miss out on their pre-season targets.
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A motorcyclist killed in a crash on the A93 has been named by police.
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Police funding cuts in Kent should be deferred in the wake of the Paris terror attacks, the county's police and crime commissioner (PCC) has said.