A late equaliser from Denis Alibec saw Astra hold West Ham to a 1-1 draw in the first leg of their Europa League play-off on Thursday.
Captain Mark Noble scored from the penalty spot just before half-time to give the Premier League side a valuable away goal, but the hosts levelled with seven minutes to play at Marin Anastasovici Stadium to keep the tie finely poised.
Slaven Bilic made eight changes to the West Ham team that lost 2-1 to Chelsea at Stamford Bridge on Monday, handing a first start to new signing Jonathan Calleri in attack.
The Argentine saw a header brilliantly saved by Silviu Lung, while Michail Antonio had an effort cleared off the line before Noble converted in the dying embers of the first half.
Antonio missed a glorious chance on the break to make it 2-0 and West Ham were punished two minutes later, when Alibec fired high past Darren Randolph at the near post to keep Astra in with a chance of a shock at London Stadium next week.
Calleri's header was kept out by Lung before Antonio nodded a corner goalwards only to see the ball hooked off the line, as West Ham pressed in the early stages for a valuable away goal.
Youngster Reece Burke's header was clawed away by Lung late in the first half, but Noble gave West Ham the lead just before the break, sweeping the ball into the net from the spot with supreme confidence after Cristian Sapunaru had handled inside the area.
Astra wasted a good chance for a 72nd-minute equaliser, when Alibec shot straight at Randolph after being played clean through into the area by Fabricio's fine pass, as they continued to probe the visiting defence without much success.
Antonio spurned a simple opening to double West Ham's lead, hitting the side-netting with the goal at his mercy after being picked out by Marcus Browne on the counter-attack, and Bilic's side were left to rue that miss.
With just seven minutes to play, Alibec collected Filipe Teixeira's corner at the near post, before turning into space and beating Randolph emphatically.
West Ham survived a late siege on Randolph's goal to hold on to the draw that leaves them still as favourites to secure a place in the group stages of the competition.