A last-gasp strike denied the Giallorossi their first victory of the campaign, and heaped more pressure on the Spanish tactician.
A late goal from Roberto Vitiello gave Siena a deserved point at the Stadio Olimpico and frustrated Luis Enrique in his attempt to land his first Serie A victory as Roma coach.
Pablo Osvaldo had given the capital club the lead in the first half, but once again a late goal means Roma remains without a win this season, and only increased the pressure on the Spanish boss.
Indeed, both Roma and Siena were looking for their first three points of the season, with Giuseppe Sannino's men desperate to banish the memory of the Bianconeri's 1-0 loss to Juventus at the weekend.
It was Luis Enrique's men who got off to the better start, patiently keeping possession, calmly recycling the ball and making sure Siena was camped inside its own half for the first 15 minutes. As has been the case in the club's previous two games though – against Cagliari and Inter – once inside the final third, Roma struggled to convert any of its chances into goals.
But it was clear that the home side was on top, and it managed to convert its dominance into a lead on 25 minutes. Marco Borriello hit the by-line, smashing the ball across goal, to find Osvaldo unmarked at the back post, ready to tap in from two yards.
Siena did manage to put up more of a fight after that setback with both Angelo and Emanuele Calaio going close, but it was a deserved 1-0 lead that Roma took into the break.
Pablo Gonzalez replaced Angelo at halftime, and the visitors seemed to open up much more at the start of the second period. Calaio was profiting much more from the Argentine's direct running, and was proving a constant thorn in Simon Kjaer's side at the heart of the Roma defense.
Kjaer redeemed himself on 65 minutes, clearing the ball quite miraculously off the line, when Gonzalez's header looked for all the world to be going in.
However, the efforts to keep out Siena proved futile on 88 minutes, as a shot from Brienza hit the woodwork, and Vitiello was there to knock in the rebound to make it 1-1, and stun the home support.
Luis Enrque's side has now collected two points from its opening three matches, level with the visiting side, which can be pleased with its battling display.