After scoring 55 on debut against Yorkshire a month ago, Ibrahim made 41 not out.
Sussex were in deep trouble at 96 for six when Ibrahim was joined by Will Beer and the pair put on 65 for the seventh wicket, the highest partnership of a troubled innings, before Beer was out to the last ball of the day.
Sussex were depleted - with eight players self-isolating because of a Covid-19 case within the camp. Of these at least two, Tom Haines and Ollie Robinson, would certainly have played. Robinson was the side’s star player with 13 wickets in the club’s only championship win of the season at Sophia Gardens.
In addition, Sussex – bottom of Group 3 in the county championship - were missing the injured Phil Salt and Chris Jordan, while George Garton was away on England duty. Oli Carter, a 19-year-old batsman and wicketkeeper, became the seventh player to make his debut for the county this year.
Glamorgan welcomed back Colin Ingram for his first first-class game since 2017 and Timm van der Gugten, with. Marnus Labuschagne and Michael Neser in quarantine.
In damp and dark conditions Sussex surprised many people by choosing to bat when play eventually got under way at 2.25. They lost their first wicket to the last delivery of the second over when Chris Cooke took a fine catch low down to his right to dismiss Aaron Thomason off van der Gugten for four.
After one ball of the third over the players came off, briefly, because of more rain, as they did again after 11.3 overs, by which time Sussex had progressed to 23 for two, Stiaan van Zyl having lost his off stump to Michael Hogan for five. By that time the floodlights were in action.
Ali Orr scored a 35-ball four before he was lbw to van der Gugten, and Sussex were 34 for four when Carter was lbw to lbw to James Weighell – a very tight decision - for three from six balls.
But then the sun came out and Ben Brown and Travis Head briefly prospered, with a stand of 41 in nine overs. When Head, who had averaged ten before this game, cut Dan Douthwaite for four to reach 22 it was his highest score of the season. But it was clearly Glamorgan’s session when, just before tea, Douthwaite had Brown caught behind for 22.
Head moved his score to 47, with eight fours, before he was lbw to van der Gugten without offering a stroke and he walked without waiting for the umpire’s decision.
Head said: “I was disappointed not to go on with it but it was nice to get a few runs. I feel I’ve worked hard over the summer. I’ve been playing all right in the T20s. I’ve had a good time in the middle in that form of the game. And I’ve been working hard in the red-ball game.
"It was nice to spend some time out there. I’ve talked to a lot of people. Hopefully the second half of the season will be better than the first half. But I feel I have contributed in the one dayers.”