By Martyn Herman
LONDON (Reuters) - Title-chasing Tottenham Hotspur need look only as far as London rivals West Ham United for a reminder of how quickly fortunes can change in football.
While Mauricio Pochettino's team will arrive at West Ham's London Stadium seeking a 10th successive Premier League victory to close the gap on leaders Chelsea to a point, their opponents are still anxiously looking over their shoulders.
West Ham left their historic old Upton Park ground on a high a year ago having finished seventh but all the optimism generated by taking over the former Olympic Stadium has evaporated during a season of struggle.
They have won only six league games at their new home and only once in 10 home and away as they limp towards safety.
Injuries and an acrimonious fall-out with top player Dimitri Payet, who was sold back to Marseille in January, have not helped manager Slaven Bilic's cause, but the loss of momentum caused by a stadium switch has proved most difficult to fix.
It is a cautionary tale for Tottenham.
They confirmed last week they will move out of their White Hart Lane fortress at the end of the season to allow work on their new 61,000-seat stadium to be completed in time for the start of the 2018-19 season.
In the interim, they will be tenants at Wembley Stadium, where they played their Champions League home matches this year, with little success. They also lost to Chelsea there last month in the FA Cup semi-final, meaning they have won only once at their "adopted home" in their last nine visits.
Pochettino is well aware of the perils of moving to Wembley - especially as Tottenham's title bid has been built on an unbeaten home league record at White Lart Lane, where they have won their last 13 matches.
"We can see from outside but we don't know the reality," Pochettino said of West Ham's troubles at home during a Thursday news conference. "Sure they suffered a little bit.
"We are aware the next season will be very important to us, our willingness needs to be bigger than this season, we need to be ready for everything.
"It's important that all staff, the club, the players know next season will be tougher than others, different, we need all the people giving their best to try to arrive at the new stadium in very good condition."
Bilic was flavour of the month last season and even masterminded a 1-0 victory over Pochettino's Tottenham - a result that undermined Tottenham's title hopes last year. Now the Croatian is under pressure.
“He's a great guy and great manager," Pochettino said.
"Always it's difficult when you move to a new stadium, the Olympic Stadium, completely different. We start to see this at Wembley, what happens when we played there.
"We must make Wembley our home and it's so difficult."
(Reporting by Martyn Herman, editing by Larry King)