Everton's expectation levels were raised before the new Premier League campaign following a busy summer transfer window that resulted in nine players being brought in, with the overall cost of the new arrivals well over £100million.
Gylfi Sigurdsson, Jordan Pickford, Michael Keane, Davy Klaassen, Nikola Vlasic, Henry Onyekuru, Sandro Ramirez, Cuco Martina and Wayne Rooney were all added to the squad and a 1-0 opening-day win over Stoke City got things off to a positive start.
However, the Toffees have won just once in the league since that victory over the Potters and are currently just two points above the relegation zone, putting huge pressure on manager Ronald Koeman.
England international Jagielka has missed the last four matches with a hamstring injury but, with fellow centre-back Ashley Williams struggling for form, a return to fitness could offer a way back into the side for the 35-year-old.
Everton return to domestic action on Sunday with a trip to the AMEX Stadium to take on Brighton and Jagielka insists the senior players need to pull together and arrest the disappointing form.
"It is a massive role for the captain, vice-captain and experienced players: to go out there and show that leadership through our performances," he told evertonfc.com.
"Hopefully once we get back from the international break we will put together a decent run and everyone will forget about the sticky start we have had."
Everton have only lost two of their previous 11 meetings with Brighton - the most recent outing being a 2-1 win back in 1983 - and punters may decide to use their free bet on Koeman's men bouncing back to form with all three points against the Seagulls.