Arsenal manager Mikel Arteta said he did not start Pierre-Emerick Aubameyang in their 1-1 draw with Slavia Prague because of other players "who had the best chance".
Aubameyang was dropped to the bench at the Emirates Stadium as the Gunners were held in the first-leg of their Uefa Europa League quarter-final tie.
The Gabon striker was later introduced in the 78th minute alongside Egypt's Mohamed Elneny and goalscorer Nicolas Pepe.
Eight minutes after their introduction, Pepe broke the deadlock following an assist from Aubameyang but Arsenal suffered a late equaliser with Tomas Holes’ header in the stoppage-time.
Arteta, in his reaction, defended his tactical changes and disclosed that Aubameyang and the second-half substitutes made the impact that was required of them.
“It was a big decision to leave some players out but we decided to play the team who had the best chance at the start of the game, and as well have some key players there to change the game when we need it,” the Spanish manager told the club website.
“I think when they came on they had a real impact, which was very necessary in this competition and they did what we expected them to do.”
Aubameyang has struggled to find the back of the net in his last five matches for Arsenal but he has scored 14 goals so far in all competitions.
When asked if the 31-year-old understood the reason behind his decision, Arteta said: “Well I cannot talk with everybody individually every week, but we try to be transparent and communicate with the players as clearly as possible for them to understand the role that they have in the game.
"When he came on, he showed the right attitude and the right commitment.”
With nine Premier League goals to his name this season, Aubameyang will be hoping to return to the scoresheet when Arsenal travel to Sheffield United for their next league fixture on Sunday.
Arteta's side are 10th on the league standings with 42 points after 30 games and they are yet to win their last four matches in all competitions.