Goosen took three from the rough beside the final pin for a bogey five at Loch Lomond to finish inside the top 20 ahead of the Open at Royal Liverpool.
'My game has been rubbish,' he said. 'I'm not going in there with the confidence I'd like to be going in with. I'm missing a lot of fairways, missing a lot of greens.
'But I'm grinding it out and hopefully things will turn my way soon.'
The 37-year-old South African has been struggling to find his form for several weeks, missing the halfway cut in the U.S. Open at Winged Foot last month after rounds of 77 and 78.
'I'm still struggling, but I'm working hard. I'm still leaving a lot of wild shots out there. My game's still a bit scrambly.'
But there are some positives for Goosen. 'At least today I made a few putts, which was nice,' he said. 'And my short game has been pretty good. I've chipped pretty well and had a lot of up and downs, which is good for this week.'
He plans to have his first look on Monday afternoon at the Royal Liverpool course at Hoylake, which has not staged the Open since 1967.
'I've heard good things about it,' he said. 'I like the British Open. Like I say, I just need to start driving a little better.
'Tiger (Woods) and Phil (Mickelson) are guys you have to look for. They're playing well,' he said. 'But it's nice seeing and playing a course nobody has played. You don't really know who has an advantage.'