Investors could be forgiven for not being able to recall the last time gold prices traded below $1,000-an-ounce, considering they’d have to scroll back to September 2009 before running into that level.

But don’t think gold is so far removed from that sub-$1,000 level that it can’t revisit that nadir in short order, warned analysts at Citigroup in a note on Monday. And they said it’s all about the dollar.

“We see no reason why gold should not once more trade at $1,050/oz if US$-DXY rises back to the 100-level (now 95.3). Nor do we see anything to prevent gold falling below $1,000/oz if US$-DXY rises above the 100-level,” said the analysts.

US$-DXY refers to the ICE Dollar Index DXY, +0.03% , which tracks the greenback against a basket of rival currencies.

An inverse relationship

Gold hasn’t settled under $1,000 an ounce since September 29, 2009, according to FactSet. Gold US:GCM6 has risen about 18% so far in 2016, one of the best gains for any asset this year. A drop below the $1,000 handle would mean a 20% slump in gold prices from Monday’s $1,250 price tag.

Gold last touched $1,000-an-ounce in late 2009

Prices have already seen some pressure this month owing to rising expectations that the U.S. Federal Reserve could raise interest rates at its June meeting. Last week, gold futures posted a second straight weekly loss, setting them on track for a 3% slide in May. Meanwhile, the ICE Dollar Index DXY, +0.03% is down 3.5% year-to-date, but up 2.4% in May so far.

Read:Gold’s slide begins a new week as Fed speakers could back higher U.S. rates

The below chart from Citi shows how the Dollar Index, has “long-term momentum behind it,” the analysts said. Another hint that the Dollar Index could bust past 100 is its strongly rising moving average, they said.

Back to 100? Maybe, says Citi

The dollar and gold’s inverse relationship is shown here:

Inverse

Investors have recently showed clear reluctance, however, to push the dollar through the 100 level, first in March 2015 and then in January 2016, noted Bergtheil and the team. The dollar’s pullback between January and April this year is a key reason why gold has managed to find strength (see section A), they said. Here’s the Citi chart illustrating that:

‘A’ notates the spot where DXY pulled back and gold rallied

Last week, a prominent market analyst Tom McClellan noted a major multiyear cyclical pattern was forming that could signal gold’s fortunes may be about to reverse. Dennis Gartman, editor and publisher of The Gartman Letter, told CNBC that there has been an “aggressive seller of spot gold” around the $1,270 to $1,285-an-ounce mark. He advised that investors not come off the sidelines for gold until after the first U.S. interest-rate hike this year.

Read: Charts reveal a bearish trend lurking in gold futures