Drug-enhanced or not, the action thriller Limitless led the box office on Friday with $6.6 million, according to early estimates. The Relativity Media movie, about an extremely attractive but unemployed writer who takes a “smart pill” to transform into an extremely attractive and successful businessman, should give star Bradley Cooper his first opening-weekend victory as a leading man since 2009’s breakout hit The Hangover. Limitless, which cost $27 million to produce and costars Robert De Niro and Abbie Cornish, is on pace to win the weekend with about $19 million.

After Limitless, the next four films are all bunched together. The alien-invasion flick Battle: Los Angeles scored second place with $4.5 million — a steep drop of 66 percent from last Friday. Within $100,000 of Battle: LA was another alien-themed movie, the new R-rated comedy Paul, which collected $4.4 million. The $40 million film stars the English comic duo Simon Pegg and Nick Frost as two comic-book fanboys who accidentally stumble upon a Seth Rogen-voiced extraterrestrial. The Friday figure is an encouraging start for Pegg and Frost, whose last two major collaborations, Hot Fuzz and Shaun of the Dead, registered opening-day grosses of $2.1 million and $1.2 million, respectively.

In fourth was the animated Western Rango, which fell a scant 22 percent for $4.3 million. Right behind it was the weekend’s third new release, the Matthew McConaughey crime drama The Lincoln Lawyer, which took in $4.1 million on Friday. The $40 million R-rated film marked the first time a studio (in this case, Lionsgate) partnered with the deal-of-the-day website Groupon. On Wednesday and Thursday, Groupon users could purchase tickets to Lawyer for a discounted $6. A reported 190,000 tickets were sold through the promotion. Check back here on Sunday for the complete box office report.

1. Limitless — $6.6 mil

2. Battle: Los Angeles — $4.5 mil

3. Paul — $4.4 mil

4. Rango — $4.3 mil

5. The Lincoln Lawyer — $4.1 mil