Arsenal stood firm in a Carabao Cup semi-final first-leg stalemate with Chelsea at Stamford Bridge.
A thrilling 2-2 Premier League draw at the Emirates Stadium a week ago was followed by a cagey encounter here.
The Blues had the better opportunities to take a first-leg lead, but Cesc Fabregas and Andreas Christensen spurned headed opportunities either side of half-time in a 0-0 draw.
Fabregas wanted a penalty after a Danny Welbeck challenge in the 88th minute, but play continued when referee Martin Atkinson consulted Video Assistant Referee Neil Swarbrick and it was determined Welbeck got the ball.