Sunderland: Gareth Barry is confident Manchester City will be able to chase down Manchester United at the top of the table as the champions prepare to face Sunderland on Wednesday.
Roberto Mancini's team have responded to their 3-2 defeat in the Manchester derby earlier this month with consecutive victories.
That loss to their bitter rivals increased United's lead to six points but second placed City managed to reduce the deficit to four over the weekend.
Barry scored in stoppage-time to secure a 1-0 win over a stubborn Reading side on Saturday before United dropped two points with a 1-1 draw at Swansea on Sunday.
England midfielder Barry, 31, acknowledges that United's home games against Newcastle and West Bromwich Albion over the Christmas period are easier than City's trips to Sunderland and Norwich.
But City overturned United's eight-point lead in the final six games of last season to win the Premier League title and Barry is adamant Mancini's side have a similar determination this time around.
"When there's a little gap it's important that you don't slip any further behind," Barry said.
"If we can keep chipping away hopefully we can be there at the end of the season.
"It's going to be a big Christmas and looking at the fixtures, they didn't fall that kindly for us, with two away games with the distances we've got to travel.
"They're tough games but we showed a great performance at Newcastle and we've got to do the same over Christmas."
City captain Vincent Kompany was on the bench for the win over Reading after a groin problem and he may be fit enough to return to the starting line-up at the Stadium of Light.
Italian striker Mario Balotelli could return from illness, while Mancini will be hopeful that left-backs Gael Clichy and Aleksander Kolarov can overcome minor injury problems.
But Samir Nasri, Micah Richards and Jack Rodwell are all ruled out until the new year.
Although United have the advantage at present, City's recent defeat to Alex Ferguson's side was their only loss in the Premier League this season and Ivory Coast defender Kolo Toure believes the champions have already demonstrated they have what it takes to retain their title.
"It's giving us encouragement because we haven't played to our best yet," Toure said.
"We are the champions, every team knows we are champions. They play 200 percent and that makes it really hard for us.
"We just keep fighting, keep pushing and we can still be better."
Sunderland winger Adam Johnson is a doubt to face his old club as City go in search of their first victory at the Stadium of Light for almost four-and-a-half years.
City inflicted a 3-0 defeat on Martin O'Neill's side in October, but they have taken just one point from their last three trips to Wearside, and their most recent victory was in August 2008.
Johnson is showing signs of recapturing his best form after struggling to impress since a £10 million move four months ago.
The England international was forced off with a thigh problem during the second-half of the 1-0 victory at Southampton that pushed Sunderland four points clear of the relegation zone, and O'Neill is keeping his fingers crossed the midfielder recovers in time.
"I'm hoping it's not too serious, but the way he limped off, it didn't look all that inviting," O'Neill said.