Universal’s “Unfriended” and Sony’s “Paul Blart: Mall Cop 2″ are providing respectable challenges to box office colossus “Furious 7,” each heading for an opening weekend as high as $18 million, according to early estimates Friday.

The micro-budgeted “Unfriended,” which expands to 2,739 North American theaters, is outperforming recent tracking of about $12 million. The chiller scared up between $6 million and $7 million Friday — easily making back its $1 million budget.

Meanwhile, U’s “Furious 7″ will top the chart in its third weekend out of the gate with $8 million on Friday for a weekend around $26 million, marking a 56% decline. Estimates showed the tentpole, which cost nearly 200 times as much as “Unfriended,” will cross the $290 million mark by the end of the weekend.

Box office forecasts have pegged “Blart 2″ on track to debut with about $5 million Friday to finish in the $15 million to $18 million range this weekend when it opens at 3,629 theaters — far less than the $31.8 million to which the original opened in 2009.

“Unfriended” has scored with critics, garnering a 66% “fresh” rating on Rotten Tomatoes while “Blart 2” has struck out with a rare 0% rating. Kevin James returns as the enforcer, with Adam Sandler’s Happy Madison label producing the $30 million film.

Disney’s nature drama “Monkey Kingdom,” narrated by Tina Fey, is opening in line with forecasts with a $2 million Friday at 2,012 theaters and should do $6 million for the weekend.