Arsenal's Premier League title challenge got off to a winning start on Saturday but the big-spending Gunners were made to sweat in a 2-1 victory over Nottingham Forest.
First-half goals from Eddie Nketiah and Bukayo Saka had the home side cruising at the Emirates.
But they were made to suffer a nervy finale after Taiwo Awoniyi came off the bench to pull a goal back for Forest seven minutes from time.
The day got off to an embarrassing start for Arsenal as kick-off was delayed by 30 minutes due to issues with an e-ticketing scheme that left tens of thousands of fans unable to take their seats in time for the scheduled 1130GMT kick-off.
Once the action got underway, Declan Rice, Kai Havertz and Jurrien Timber were handed their league debuts after joining for combined fees in excess of £200 million ($254 million).
However, three points for the home side was soured by an injury suffered by Timber as he pulled up early in the second half.
By that point the game should have been over as a contest as Arsenal sprang out of the blocks.
Mikel Arteta's men are looking to go one better after finishing second behind treble-winners Manchester City last season.
City cruised to a 3-0 win at Burnley to open the Premier League season on Friday night and Arsenal should have followed suit rather than holding on for the final whistle.
Forest have their home form to thank for staying in the English top flight last season on their return to the Premier League after a 23-year absence.
Steve Cooper has targeted an improvement to their poor return on the road, but they barely laid a glove on the hosts until the introduction of Awoniyi and Anthony Elanga late on.
- Martinelli magic -
Forest's rearguard resistence lasted 26 minutes until the visitors were undone by a moment of magic from Gabriel Martinelli.
The Brazilian's turn took him past two defenders before the ball broke for Nketiah to drill low beyond Forest debutant Matt Turner, on his return to the Emirates after leaving Arsenal this week.
Turner had no chance with the second six minutes later as Saka cut onto his favoured left foot and arrowed a trademark strike high into the far corner.
Timber had recovered from a knock at the end of the first period to take his place at the start of the second.
But the Dutch international then pulled up holding his hamstring and had to be replaced just four minutes into the second-half.
Awoniyi was surprisingly left out by Cooper despite scoring in Forest's final four games of last season, including the winner against Arsenal that secured his side's survival in May.
The Nigerian continued his scoring streak by turning home at the near post after former Manchester United winger Elanga sprinted the length of the field from an Arsenal corner.
Arsenal held on through seven minutes of added time, but it was a far from convincing start to their quest to become English champions for the first time in 20 years.
kca/bsp
