Fly-half Freddie Burns kicked 17 points as Bath survived a brilliant grand finale by London Irish at the Madejski Stadium.
A brilliant effort from Irish, particularly late on, put them agonisingly close to winning the game.
Replacement Scott Steele's 75th-minute try, converted by Greig Tonks, added to a first-half touchdown from full-back James Marshall and two penalties by fly-half Tommy Bell to give Irish a chance to snatch victory.
Burns' contribution was big as he punished the Exiles for their mistakes as he went through the book with four penalties, a drop goal and the conversion of centre Matt Banahan's first-half try.
It was a good first half of rugby that saw Irish ahead when Bell booted a penalty from 28 metres.
The lead lasted five minutes before Bath, without eight regulars who are on international duty, went ahead. Good work on the left touchline from wing Aled Brew saw the Welshman put the ball inside where weak Irish defence let Banahan through to the line.
Burns booted the conversion and added the first of his penalties on 13 minutes.
Irish, though, hit back and began to play some good rugby. An attack 30 metres out on the left by Bell saw him link with wing Joe Cokanasiga and send Marshall in at the corner.
The topsy-turvy game turned back towards the visitors as Burns dropped a simple 20-metre goal in front of the posts, and landed a massive 50-metre penalty from the halfway line as his side took a 16-8 advantage.
Yet Irish, who were missing six men involved in the Test match squads this weekend, turned up the heat and looked nothing like the Premiership's bottom side when they had Bath on the rack as the interval approached.
No. 8 Blair Cowan had a try ruled out and Bath scrum-half Kahn Fotuali'I just managed to put Marshall in touch when he looked bound to score at the corner.
Irish had the final say of the period when Bell kicked a penalty to make it 16-11 at half-time.
Burns increased Bath's lead with a great touchline penalty minutes after the restart and another penalty from in front of the posts on the hour.
Bath's 11-point lead looked to have won it until Steele set up a grand finale with a try converted by Tonks and, with one try to win it, Irish were rampant.
Irish put Bath on their own line and looked odds-on to get the winning try but the opposition defence held up heroically and an Irish penalty gave Bath the victory.